I always have been having strange hives and think I may be pregnant, and after doing a little research online, I saw that pregnant woman can get hives/rash, that sometimes starts on the stomach( which mine did, a small patch) and spreads to thighs, arms and breast(mine just on my arms and it comes and goes, small red itchy bumps)
I am still unsure if I am pregnant or not, I just wanted to let you know I was experiencing something like you and I could possibly be pregnant..
I'm sure that didnt help too much! Sorry!