Bumps on butt?!

Hey, so does anyone else get bumps on their butt when you go to bed? Whenever I go to bed, about 20 minutes in I start feeling these “bumps” on my butt and they literally look like big pimples but without the “white stuff” coming out. I always think they’re regular pimples so I scratch them off so they can pop, but it doesn’t give off that “popping” sound/feeling. By the morning they’re flat and I’m not red anymore.

This happens all the time, and I’ve googled it and google mainly says it might be “bed bugs” but I don’t have that in my bed.

I wash my sheets, blankets, and pillowcases often. I’ve also checked my bed for them and I don’t ever see that, so I definitely don’t think it’s bed bugs.

Thanks for the help.