Is it possible to start to feel better in the midst of having appendicitis?

my boyfriend was pretty sick for a few days, fever, diarrhea, nausea, headache, no appetite, sleeping all day. he is starting to feel better now (fever gone, diarrhea has stopped, appetite is back, etc.) and has gone back to work, but today he says he has a pain in his lower right abdomen. is it possible that he had/has appendicitis? or with appendicitis do you just get worse and worse (i have heard it progresses rapidly)? i mean it might not be appendicitis at all but i was just curious if it's possible that he has it.