I have developed a rash on the underside of my belly, I know this is probably a heat rash or just because my skin is stretched so tightly because of my huuuuuge guts, but it's driving me crazy!!!!

I have been putting Sudocream on and this helps a bit, but I was wondering whether it is safe to take any antihistamines at this stage of pregnancy. And I know scratching just makes it worse but I can't stop myself!