How do you move on when there's no path left?

All that blood. It couldn't be. Not him. Not Sherlock. "No!" John pushed the people aside and stared down at the lifeless body. That wasn't Sherlock. It couldn't be him.
It was him. Of course it was. He couldn't have turned into anybody else during his fall...
No pulse. It was like John's heart had stopped the moment Sherlock's did. "No. No!" His head was spinning. It was dark, cold. Where was he? What was going on? He saw his best friend walking away. He ran after him, but he didn't come any closer. He was running as fast as he could, but it was of no use. "Sherlock, wait! SHERLOCK!"

John sat straight in his bed. He'd screamed out again. He was shaking, cold sweat was running down his forehead.
The nightmare wasn't the worst. Waking up was worse. Waking up from one nightmare only to dive into the next... Only that this one was cruelly real.
It was quiet. It always was. John was always listening to the silence. The silent whispers, the echo of his friend.
It had been one year. One whole year since he watched Sherlock jump into his death. One year and still it hurt so badly it left him breathless.
John forced himself to stand up and get dressed. The first week after Sherlock's death he hadn't done much. He stayed inside most of the time. Staring at the empty seat in the living room where he used to sit.
But after a while he couldn't do this anymore. He needed distraction, and especially he needed money.
Of course, it didn't matter what he was doing. The emptiness never vanished. He'd lost many men he used to like back in his army days, but this was different. This was something he wouldn't ever recover from. He knew it. And he was glad he did. It was sort of like paying tribute to Sherlock.
John stared at himself in the mirror when he brushed his teeth. Practically waiting for Sherlock to come in without knocking and going in the shower, ignoring the fact there was another man there like he always did. But he didn't come.
John made two cups of tea when he sat by the table. No one ever drank the second cup. But it felt wrong not to brew it.
He hadn't changed much about the flat. There were unfinished experiments lying around. A magazine Sherlock never finished. His violin on the table, only the little webs suggesting that it hadn't been played in a year. Just in case... Just in case he'd come back. Sherlock would be furious when he came back and John had changed anything.
It was stupid to think that, John knew it. Sherlock wouldn't come back. But it was the sentiment that made him think like that. Sherlock always found a way... So why not now?
He took his jacket and left the house. A quick snack at the bakery before he headed to the clinic. He had a fulltime job as a doctor now, but they didn't ask more of him than he might want. He mostly got the hypochondriacs and people with a cold. It was the most dull work he could imagine, but at least he did something and earned a little money.
Lisa, the receptionist, greeted him with the biggest smile that he returned half-heartedly. This woman was always in a good mood, no matter what daytime it was or how the weather was or whatever. That was probably good as some sort of opposite pole with his depressed behaviour. He didn't have the feeling his patients really liked him, but to be honest, he couldn't care less.

It happened when John was just listening to the fourth man thinking he had the pig flu (Were they old-fashioned? John thought that disease was already 'out'). His phone was beeping with a message. He looked down on the display. It was the name of someone he hadn't talked to in a while.
"We need your help. Call me asap. –GL"