I have never had appendix troubles, but I have a friend that had repeated pain problems. They were treating her for gynelogical problems, but it turned out to be a "hot" appendix problem. Once they figured that out and did surgery...problem solved. It took about 6 weeks to figure it out, however.
I have had several "leaking" ovarian cysts....the pain is incredible. However, the pain never occurrred below my navel, but on the left side about where my left ovary is located (it occurred once on the right side). After the initial severe pain, a residual soreness remained for days.
Hope you figure it out soon.