It's kind of cute that after getting hit by a hard object in the head hard enough to render him unconscious for a relatively good amount of time (based on the school nurse's words), the dude is still in the school infirmary. In reality he would be in a hospital and would have got a CT scan done already.
What we see here, from the 14th page onwards, may as well be not real, but rather some dying dreams or adventures in Comaland for the protagonist.
That includes being in the infirmary instead of a hospital, and being very muscular, and even more improbable things that surely will follow in the future.