Could this be something serious ?

Hey everyone so my 4 month old pitbull was sleeping and she sleeps a little funny . So I noticed a little pimple she had next to her private area and it had a little pus . I looked online and got different answers so do you guys think it’s something I should be worried about ? Has anybody else’s dog had this before and would like to give me some insight on it ?!?! Anything helps so please comment and tell me what you think or know .