Do I Have Allergies?

For about the last ten yrs I have had these horrible symptoms with numerous tests done but no diagnoses. I have been tested for lupus, cancers, and many other things. I have been to a rhuematologist, ENT and I have an appt. with a GI and Derm. for the second time. My symptoms come and go and I am not sure if it is after I eat a certain food or not. I do know that I am allergic to things such as latex, neosporin, nickel, sulfur, and other things. I also get rashes if I stay in the sun for too long. My grandmother, mom(non-hogdkins-lymphoma), sister(lupus), and brother all get the same symptoms. My symptoms are as follows: I will get very nausease and vomit often. Mostly in the am right after getting out of bed. During the day I will have stomach pain, I feel like I will have diarhea, I run to the bathroom and I am constipated and then after a little while later I get the pain again, I run to the bathroom and it is diarrhea. I get headaches just about every day and I am lucky if they do not turn into migraines by evening time. I also get rashes. They will usually appear in back of my throat, on my arms, thighs, on my sides, and they will start out as just one or two bumps and they gradually spread to be the size of a softball. The center of the rash clears up while the outer ring of rash continues to spread. My hands will also get rashes on them but it is different from the rashes I get on my body. My knuckles actually get this thick crusty stuff on them and they get these deep crevices where my creases are. They bleed and it is almost unbearable pain. I will also sometimes have a hard time taking a deep breath(hurts my left shoulder and back between shoulder blades. Lymphnodes often swell up also. I am tired of tests and now I have a barium test scheduled and I really don't want to do it. Anyone have any suggestions? Should I maybe get tested for food allergies?
Thanks for your time.