I’ve had a rash on my neck/upper chest for about a week. Originally the rash started as big, red, itchy bumps; they’re smaller in size and not as itchy, but still annoying. I’ve been applying hydrocortisone cream, but I don’t know what caused it.

Itchy rash. I suspect an allergic reaction to something that came in contact with your neck and upper chest. It could have been clothing, jewelry, perfume or cosmetics. I would add to your treatment the taking of an antihistamine like benadryl(can cause drowsiness) or claritin(nondrowsy). If the rash persists you should consult a physician or a dermatologist for a prescription strength corticosteroid ointment.