heat rash

I went to take a bath last night and when I took my shirt off I noticed I had whay looked like a heat rash on my belly around my belly button and below and above it, it wasn't bad but it was noticeable and once I got in the bath obviously the warm water made it a little worse and it went even higher on the top of my stomach, then after I got out it had been maybe 10 to 20 mins I noticed I had it on my sides on my love handles and it didn t spread anywhere else idk why I got it in the first place but my question is can this be a sign or first sign of pregnancy the reason I ask is because I never do this and the last time I did have this happen I was pregnant but I already knew I was pregnant so I figured it was because of all the extra blood flow and etc... last month I had a really weird "period" they always last 7 days and I always have bad cramps but I started 4 days early and I spotted for only 3 or 4 days and I only cramped the night I started spotting and it was very light cramps and never intensified and I didn't cramp anymore I've took test but they were all negative so I said screw it and I'll wait to see if I miss my period this month which I'm not due to start until Christmas but last month and now again this month my right nipple hurts and that never happens even before my period is due and I've been peeing alot more I've noticed so I was just curious if this has happened to anyone before u with the heat rash and u ended up being pregnant?