toddler hives

My son is almost 2 and has had hives for 1 week now. his doctor said to use benadryl and if its still there after a week i can call urgent care since it will be the weekend. so now we'll be waiting at urgent care to see what they say. would rather see our own doctor but not sure if I want to wait till after the weekend. he has no other symptoms besides the hives. anyone with similar experience?