thrift find

so I bought these yoga pants at the thrift store, I thought it was a really good find, they looked brand new super good condition okay so

I washed them before putting them on (of course) but idk, Everytime I've worn them i notice I smell. like it's from my down stairs part, I smell sweaty and gross and idk. That never happens to me, only when I wear these pants.

Any clue on what it could be? anything I could use to get rid of the smell? should I just throw them away?