What Causes Painful Fingers And Back Area And Tender Breasts?

I was diagnosed with gastritis yrs ago , I also was diagnosed with hashimotos and arthritis , what can I eat to relieve pain in my body. Everyday I wake up to pains in my fingers and back and I get a pain on my left side under my left breast, what causes this ? I do not eat fatty foods or drink milk, or alcohol or use drugs. I eat mostly cereals, pastas, salads, chicken or turkey burgers. I only bake or grill on the george foreman grill my meats. I dont eat spicy foods either, I drink rice or almond milk , decaf teas, or herbal teas like chammomile or ginger tea, what can I eat ? Are sweet potatoes and mashed potates ok to eat, I read nightshade vegs should be avoided, is this true? THANK YOU ! Nancy