What is this pain in my abdomen?

It's on the right side, and isn't really a pain in my abdomen, per se. It's on both my lower right abdomen, near my belly button, and on my lower back, in about the same position. I feel it whenever something brushes against my skin, so it's more like a sunburn or a nasty bruise, except there's no skin discoloration. I've also been feeling nauseous lately, but it's been off and on. My mother thinks it might be appendicitis, and we're waiting to see if it progresses, but I just wanted a second opinion. I haven't changed my diet in the past couple of months. I've been a bit more stationary recently because of the summer, but my exercise habits haven't changed otherwise. I haven't been hit in the area. I don't have a fever, though recently I had a very mucous-y diarrhea that was most likely brought on by me drinking a lot of fluids on one particular day, though I'm not for certain. The pain is constant, but it doesn't hurt when I press, only when I touch the skin. If you can offer any insight into what it might be, I would be very grateful.