Sakura caught his fragile body in her arms, shocked at how little he weighed and just how dangerously high his fever had spiked. He was breathing, but it was labored; she could hear the blood crackling in his throat with every breath. We need to get you out of the cold, immediately...her medical oriented mind calculated furiously, and she leapt with ease and strength to the tree tops.
"Sasuke, stay with me!" Sakura cried as she sped toward the cave she was camped at.
His shallow gasps for air only became fewer. The sweat beaded on his forehead despite the fact he was freezing.
"Please, Sasuke...don't give up just yet! I - "
This is what Tsunade must have felt...
Somewhere in the recesses of her mind, it hit her. She pictured the younger Tsunade, frantic to save the life of her love, Dan.
Please, Sasuke, if you die...I won't be as strong as Tsunade, I won't be able to keep going anymore.
The tears streamed down her face as she pushed her chakra into him with all her might.
Hurriedly she laid him down on her pallet and covered him up, then fumbled around in her pocket to find and scratch her flint rocks together to make a fire beside him; all the while she kept a hand pulsing healing chakra into his throat to keep it clear and ensure he was breathing.
"Okay, okay," she breathed, trying to calm herself and assess the situation.
This situation...is so much more intense...because it's *him*...
The entire fate of the any future Uchiha clan rested in her hands.
She cooled his fever with a wet rag upon his forehead, simultaneously using her chakra to coax the fever down. His breathing was so labored she felt compelled to manually assist him.
The blood running from his throat still had not ceased; she felt it pooling on her lap where his head rested.
Using her characteristic green energy she probed his throat looking for signs of trauma, or anything.
To her shock, her dismay - there was nothing.
Where is this blood coming from...?! she shook her head.
She searched around harder, making note to continue pushing chakra into his own body.
"Alright, Sasuke...," she whispered gently to him, "Hang in there...I'm going to find the cause of this..."
The hours passed as she frantically searched every one of his internal organs, unable to find anything. The sun began to set, and with it the temperature dropped. She grasped a nearby log and tossed it on the fire.
He slipped in and out of consciousness that night. Each time he awoke she hoped he could tell her something, anything, about where pain might originate or when it started, or if...he knew anything. But each time he succumbed to his unconscious once more.
Itachi had mentioned he had it as well. It could be hereditary. Yet, Itachi had given her no clues about the disease, and she was sure that if he knew anything about it, he would have told her. He must not have known anything, either, except how it felt...
She continued her search for anomalies the entire next day, while continuing to stabilize him with her own chakra. She checked his eyes extensively, knowing the effects of Sharingan overuse. Yet to her dismay, she could find nothing.
That second night, he began to stir.
She avoided gazing at his face, afraid of the pain she would feel when she saw his face again. She avoided his eyes, and continued diligently on her work.
"Hn..n..." he groaned, and Sakura could feel the blood rise again in his throat. He shuddered painfully.
"Shh...don't speak, Sasuke-kun," she warned him sadly, "Just rest. Go back to sleep."
She felt his half-lidded eyes fall on her, for a moment. Then he lay still.
The blood rising in his throat, as painful as it was, proved useful in allowing her to target the source of his blood...his lungs.
She continued searching while he lay unconscious. Using her other hand, she grasped tissues from the desk and gently wiped the blood from his chin and mouth. She possessed so much love for this man below her, that it hurt. Hurt to see him like this, knowing he spent the last years struggling alone.
By the third night, she was beginning to sweat. The amount of chakra his body was demanding was taxing on her body, not to mention she hadn't eaten or slept.
By the fifth morning, she had found it: trauma to alveolar capillaries.
Probably from the Sharingan...
"I found it, Itachi," she found tears rolling down her face with joy, "I know what it is..."