As you explain you are fine and to a lesser extent hint at being off worse your Robed doctor speaks.
"..Right then so here is the deal. I am going to keep you here indefinitely until you can convince me you are ready to return to class. I already used my magic to infuse medicine in you so physically you should be fine by tomorrow morning but of course you can stay as long as you deem your health need it. I remember staying in here to just meditate when I got injured in a tourney once.
As your caretaker, I am also to be convinced by you of your mental state. Right now I think your loopy from the pain killers which is fine. Any questions Novice?"
Maybe being funny during a serious injury wasn't your brightest idea but hey at least you have an excuse not to do any homework. Although now you remember you didn't have any and will most likely need to spend time to catch up after being away from god knows how long away from class. However, the longer you stay the better you will feel when you return.
How long should you stay?
Short: Till the morning where you'll get the Doctor to chill out. That said your body may be a bit wobbly and people around here are not above beating down on you for pleasure. Plus, you don't really feel like seeing your dorm room mates.
Medium: During the weekend. Your body will be able to walk around with out any extra help for sure.
Long: Meditation and Fire magic are your only classes. You can just meditate in bed and work on focusing for your rematch re-testing.