I had a very bad dry skin for first pregnancy. I didnt use powder at all. Try Cocoa Butter for dry itchy skin and put twice a day. If this persistent, request for QV Moisturiser which helps to tackle dry skin. It will soon go away once you reach second trimester, if not till third trimester.
I applied tons of bio oil or clarins oil on the rash and let it aircon blast 🤣