Everyone who has seen the promo knows House runs. Everyone also pretty much "knows" this is unlikely to last forever.
My guess is that before, say, episode 8 something will change. ( Note : apart from the promo I am staying far far away from all spoilers )
Here is my take on how that might happen.

Edit - almost 10 years later, removed some rambling/typo's and revised a few minor things. No big changes.

""Have you seen House ?"

Wilson was getting a little worried, no one had seen House today yet.

He had called, but no one had answered. Cuddy had called, and still no one had answered.

House lay flat on his back staring at the ceiling.

This was not happening, this couldn't be happening.

This shóuldn't be happening. And yet, there it was.

Scarily familiar, scarily ... there.

Scarily, obviously, there every time he moved.

He didn't want to have to deal with it.

Not now. Not ever.

Not again.

Not after...

Not after everything had been better!

Had been good. Had been ... happy.

But there was no denying it.

His. Leg. Hurt.

He had to deal with this, he had to figure out what to do.

He had woken up at 6:30.

Instantly awake. And instantly knowing what had woken him up.

It hadn't been too bad then. Just a hint of pain. More an unease, really. An unease that he wanted to ignore.

But he had been awake ever since, scared, and mad as hell.

He wished he would fall asleep and wake up with it gone.

Told himself this was not happening!

But it was, and it had gotten worse.

When he went to use the bathroom at 7:55 he couldn't walk normally. Couldn't put his full weight on his leg.

Walking made it worse too, so he had quickly gone back to bed.

Panic creeping in, and wondering if he should take painkillers or not.

Wondering if he even still had some at home.

Wishing he hadn't – somewhat ceremoniously – thrown all his canes away after 8 months of freedom.

At 8:16 the first sharp muscle spasm had hit him.

And then he knew.

And he knew for sure.

Wilson hesitated for a brief moment, then knocked on the door. "House, are you there?"

No answer.

He tried again. "House, I know you're there, your bike is out front."

"House? Open up!"

"House! Are you ok ?"

He paused, listened. Still nothing.

He took a credit card out of his wallet, feeling stupid. On TV this always worked. He looked around to see if someone was watching. Silly, it was not as if he was breaking in. Or was it ? What if House really wasn't home?

But he had to make sure.

House was known for not answering his phone just because he didn't feel like it, but he always eventually answered if someone repeatedly called him. Now he had ignored 6 calls, more if he counted Cuddy's.

He messed around with the credit card. It didn't work.

Of course it didn't.

He started knocking on the door again. Louder.

Banging.

One of House's neighbors gave him a nasty look as he poked his head out of the door.

Wilson turned to him and asked " Sorry. Have you seen House today ?"

The neighbor shrugged a 'no', and went back inside. Wilson sighed, and knocked again.

"House! Open up, I know you're in there. If you don't open the door I'm calling the cops, or ..."

He didn't really know, but short of breaking the door down he was running out of options.

And then he heard a sound coming from inside.

He tried the doorknob. It was of course still locked, but the stumbling sounds were getting closer.

"House..?"

Softer, more hesitant now.

What if it was some burglar, ready to smash his skull in the moment he...

The lock flicked and the door opened.

And there was House. Still dressed in his pajama's.

Pale. Clammy. Leaning against the wall. Looking... looking very unwell.

Wilson entered and closed the door behind him. "House..? Are you sick? Why didn't you call?"

House looked up at him. He was...crying ?

"What...? Did someone die? Who...?"

And then House took a step. And Wilson knew.

For a full minute Wilson couldn't do anything.

He couldn't speak, he couldn't move. He could only stare at House in disbelief.

When he finally spoke his voice sounded strange. It was not his voice, so soft, hoarse, and far away.

"House ..."

House stood near the door, leaning with one hand against the wall, swaying on his legs.

"Dizzy", he said.

Wilson reacted almost automatically, supporting House, letting him lean on him.

Guiding him, half carrying him, to the couch so he could sit down.

"Did you take something?" Wilson asked suddenly alerted.

He grabbed House by his wrists, checking the insides. Nothing.

Stupid really, if he had cut his wrists there would have been blood. But an overdose of pills...?

House too knew what Wilson meant. Not ... yet. I thought about it.

"I can't do this Jimmy, not again. I.."

House just sat there, a miserable shaky heap of a human, his head lowered, one hand resting on his leg, clutching at the cramping muscles.

"How? When... when did it start?"

"This morning."

"How bad is it ...?"

House shrugged. "What does it matter? It is... back."

Wilson's mind was racing, going over all the options.

"Do you have any Vicodin here, or anything else?"

Wilson switched thoughts. "No... you need to go to hospital, you need..."

God, he knew what it was that House needed, and he could not give it to him.

"Wilson, I can't do this again", was all House muttered.

He didn't even react to the word hospital, didn't even protest.

This was bad.

This was really, very, bad.