Bump/soreness on butt cheek (TMI warning?)

I'm going to ask my OB about this on Tuesday but wanted to check in- in case any of you are experiencing this or can shed any light.

That night I noticed that actually I had a red 'pimple' on the middle of the butt cheek- which I never get- so I guess that explained why it felt sore. It continued to be sore yesterday and today it really is quite sore- I did a lot of physical work at work today and that butt cheek is feeling just how I described it before- sore like it's had a big workout and the whole muscle is sore.

It doesn't feel like just the pimple or just the skin on the surface it feels like the whole cheek is sore down in the muscle. After all that work I was almost limping on my way home. So tired and sore. I don't know if this is a pregnancy thing or not but I assume it is because I've never had it before.

The pimple doesn't look that bad in the mirror and it's just red and not too big- I can cover it completely with my fingertip. It doesn't really hurt to sit upon it. It hurts when I get up and take the first couple of steps my whole butt cheek feels really tender and sore in the muscle.