Help?? Pimples when I shave??

I'm Mexican and Hungarian, so I get a little hairy, and it's dark and I'm not very tan in my butt area. Idk if this is weird but I've shaved my butt just because I wanted it to be smooth and noy hairy, but every time after I shave, it breaks out with a lot of pimples! The first time i did it I didn't realise it was because of shaving, i thought it was from wearing a bikini too much since it was during spring break. After that, the pimples slowly faded away but never totally vanished. THEN, I shaved again because I was having sexy time and the next day IT BROKE OUT IN SO MANY PIMPLES. I almost started crying. My butt looks horrible now and I just want it all to go away. 😔 Does anyone have any tips to get rid of it ASAP?