Get Your Dog Care Questions Answered by Experts
Okay, then right now I would be less concerned about the eating the underwear ( and not concerned about STDs at all). What I recommend is calling your vet in the morning and getting a urinalysis. If she is having an urgency to squat more and needing to go out and uncomfortable...she may have a urinary tract infection. It makes her have a burning sensation and need to squat and she probably doesn't know why...
A urine test will help diagnose and then antibiotics can be started. If it is negative, your vet can suggest further testing. This is not usually something they just get over, but tomorrow being Saturday, you should be able to find a vet open in the morning.
Let me know what further questions you may have.
Dogs can get dog STDs but not human...and not by digesting underware. If there is sexual contact with the animal, there are other issues to be discussed...but no they can not acquire human herpes or other type STDs.