First of all, is he really feeling fine? I’ve gone to work feeling like death because I didn’t have a choice. Maybe he’s doing the same thing.
In any case, when you find out he’s about to go to work, you can tell him you’re happy he’s feeling a bit better than he was in the morning and you can’t wait until he’s feeling well enough to go back to learning with you. If you want to push it, you can ask him for an estimated date when that will happen.
You can also ask him if there is anything you can do for him.