I've continously been breaking out in hives throughout my entire body and Benadryl (diphenhydramine) hasnt been working. Should I go to the hospital?

Allergic reaction. Unless u r having difficulty breathing/ swallowing or swollen lips, etc your pcp or an allergist should be able to evaluate u & treat cause. If u r having any of the above, by all means go to er. Assemble list of meds, otc meds, supplements, new detergent/fabric softener, soap/body wash/shampoo, perfume/ body spray, new foods/drinks; also try to pinpoint when hives 1st began.