Hello, I'm Alicia. Thanks for your question, I'm happy to help you today. In my opinion, I don't think you were wrong to not specifically ask if he was feeling well, because he gave you the indication previously (the day after he had pain in his foot) when you asked that he was feeling better. "Are you OK?" is the normal question that most people would probably ask if they were in your shoes, because that also leaves the door open to other possibilities, besides the foot pain. And indeed, asking if someone is OK also (again, in my opinion) includes questions such as "Are you feeling well?" So I don't feel that you were in the wrong here to not specifically ask.
And as a side note, because you say that he does at times have a tendency to have bad moods, it's normal that you would have assumed he was sulking and that you might have assumed that his behavior had something to do with that and not with the foot pain. I hope that helps. Please let me know if you need further assistance. Best wishes.