Karina has an inflammatory disease of her gastrointestinal tract that causes her to experience cramps, joint pain, and diarrhea. her diagnosis is

I believe Karina could be diagnosed with ailment.

Ailment is actually a very common form of illness because around 60% women experienced this symtoms on their menstrual cycle.

Due to the the nature of this illness, it would eventually gone on its own even after you don't do anything about it.