Little rash with white heads?

i have a little rash that just looks like a line of tiny white heads on the top of my pelvic bone right where the top of my pants are. i am allergic to nickel so sometimes when i would wear belts i would get an itchy rash right in the middle where the buckle was. i recently got a belt that has nickel on the side of it right under where the rash showed up. ive moved around to see if somehow the nickel has been touching my skin and it doesnt seem like it has been. also the rash seems different this time. it doesnt itch as much as it is just a little uncomfertable. any ideas what it is? could it be from sticker bushes somehow? or being sweaty in the heat? ive had it for 2 days now