I Have Been Taking Diphenhydramine 50mg (was Given In ER

I have been taking Diphenhydramine 50mg (was given in ER when I had reaction to antibiotic. I had full Rx because it cleared up after they gave me IV. I have taken 2 for arm red,swollen, hot to touch, and whatever made little thin blisters. Itches REAL bad. So my kidne called in RX for Hydroxyzine HCL. 25mg. Are they same thing> Dont know whether to switch because thats when I become allergic to that medicine. I have had severe reaction to :Levoquin, Bactim, and Cipro .