He felt like absolute shit. If there was a doubt before there was no doubt now, he had been poisoned by the blue blooded creatures that he killed yesterday. After killing them he was able to climb down to get water for his canteen and clean himself off along with cleaning his wound and then he was able to climb back up. But he was not able to hunt, when he got back to his tree he felt lethargic so he climbed up and fell right asleep.
Now as he was waking up felt pain blooming throughout his entire chest but with the worst of it centered around the injury he had sustained before. Unfortunately he could not go to anyone for help and trying to find a remedy without any knowledge would do more harm than good. So he had to hope his body either fought it off or managed to hold out until the last day.