Since the rashes are lasting for less than 24 hours we are dealing with urticaria
If you have this problem for less than six weeks, then we will call it acute urticaria. If the duration is longer than six weeks then we will call it as chronic urticaria.
Oral antihistamines and topical calamine
lotion will be of help. The type of antihistamine and duration of treatment can be best decided by your doctor. He/she might also opt for routine investigation. Please consult him at the earliest.