SPREADING RASH/HIVES

[Sub542]

So I've had a rash spreading for about 2 weeks now. It originally started with minor bumps on my underwear lining.Heat and sweat made the skin more irritated and helped it spread. I'd compulsively scratch whenever drifting in sleep. Some bumps have started to scar and become scaley. About a week later a rash started appearing on my neck. I recall waking up drenched in sweat and a minor itch on my neck. I mildly touched it throughout the next couple days without any noticeable changes. Today I visited a water park and now have noticed it spears down my neck and now starting to get some bumps on the left side of my neck as well by the collar and back of my right armpit as well. They itch severely and often burn whenever hot or sweaty. I'm worried their might be something more serious then a heat rash but want some kind of consultation or something before heading in for a check up. Any feedback is greatly appreciated  thank you for your time :)