My daughter developed a skin rash, red, swollen areas various shape and size. got anti-hestamine from pharm, got better, now back. must we see a dr?

YES: You will need formal allergy testing, especially since the nature of this skin condition being recI suggest pediatric and/or allergic medical conditions.

Maybe: The rash sounds like it was triggered from something she ate or something that affected her whole body rather than a local contact agent.The whelps would be expected to return for the 3-4 days the body uses to process the agent when an antihistamine wore off. If you know the new food/possible trigger you can just avoid it in the future. Formal allergy testing might reveal one or more such agents.