my butt cheeks is covered in feces but only when I sweat

i know this is kinda gross but I don't know what else to do. To start things off I am 24 and the work I do requires a lot of sweating and driving at times. It started about a couple months ago that after I had a bowl movement it felt like my anus didn't close all the way. I would go back to work after I was done and sweat just a little bit and go back to the bathroom and my butt cheeks would be covered in feces. Only when I sweat though. So I stop pooping at work and just did it at night when I knew I wouldn't sweat. But know the times I am driving for a long period of time. My pants smell horrible. Like I pooped in them. But I didn't and I didn't have any feces between my cheeks. Just the smell would be all over the rear end of my pants. This is almost a everyday thing.  When I go back to my work office I try to run trough there as fast as possible so nobody can smell me. It's embarrassing and I don't know what to do. I'm still really young and don't want to be stuck with this for the rest of my life. I don't know if this matters or not but I haven't had a good solid bowl movement in a while earthier.  When I poop it feels like I'm not done, but I am done. And my anus somethmes hurts after I get done pooping (the times I think my anus doesn't close all the way). Does anyone have any advice, or know what medicine can help, or know what exactyl this problem is. Thank you