Is anything else given to dogs for allergic reaction besides an antihistamine? ?

My vet didn't know what was wrong with my dog. I personally think he is having an allergic reaction to tick bites. Nymph tick infestation outside. He has tachypnea, angioedema to his entire body , and loosing hair. This happened thursday overnight n she only gave him a steroid, an antibiotic and a stomach protection tablet... I haven't seem any progress only more erythema to his body n more hair loss. Can I try an antihistamine? Will the steroid he is already on have gotten rid of his allergic reaction if that's what it is. Pls help me I dot want him to die.