I Have Been Having An Occurance Of Fairly Severe Pain

I have been having an occurance of fairly severe pain in my upper middle abdomen...right under where my ribs meet, and pain radiating under my right jaw... for several years. It only happens a few to several times a year...not often. But when it does, I cannot keep a normal expression or hold a normal conversation, etc. It is hard to keep still - It is a kind of squeezing type of pain. I can feel it coming and it gets worse quickly. It lasts a few to several minutes. Sometimes it subsides for a short time (like maybe 30 seconds to a minute) then starts again, and may repeat several times. Then it goes away and may not occur again for several months, or may happen several times that day or over the next several days. It has been happening more frequently the last few months or so. In addition to this, about 2 months ago, I started having horrible sudden diarrhea about 30 to 45 minutes after eating. It seemed to happen mostly after I ate a salad, but sometimes after other foods. I would have no cramps or warning, it would just suddenly start coming out, and I might have diarrhea 8 or 10 times that evening. A couple of times, I had flu like symptoms afterwards...skin hurt, chills, body aches, and I could swear I was getting the flu. But I would be fine the next morning. I also have been having an achy back, up between and under my shoulder blades, mostly on the right side. I went to the doctor, and he said he thought it was probably gallbladder, but I just got my ultrasound results and it said it was normal. My stool color has changed since all this started with the occasional diarrhea a couple of months ago, to more of a lighter, kind of yellowish brown color instead of darker brown and more solid. I have cut way down on salads and that has pretty much taken care of the diarrhea episodes it seems. What else could it be since the ultrasound came back normal?