Pimples/Rashes on the Body. About?

I was diagnosed for Irritant contact dermatitis on my penis 2 days ago and I had physically consulted a dermatologist. They have given me Bilastine Tablets 20 mg & Fusidic Acid and Hydrocortisone Acetate Cream. I have been taking these medications only for the past 2 days and I can say that symptoms on my penis i.e., the swelling, itchiness and redness has reduced to 80%. But unfortunately on the other other end, from today morning I've developed pimples/rashes on my entire body as per the attached pic. By the way, the rashes does not itch at all. They only itch when I try to scratch on them. So, can anyone please tell me why I've developed these rashes? Are they side effects of using these medicines? If yes, which medicine should I stop using? And is it something that I need to be worried about?