Great work! One thing to note is that most of the time "I feel bad" is used to mean "I am sorry" or "I feel guilty." I am not saying you made a mistake, but "I feel bad" is not usually about how we feel physically, but rather emotionally. So you can say "I feel poorly" or "I feel awful" or "terrible" — these are commonly used. But they are, of course, usually exaggerations. I hope this helps!