Can a yeast infection cause pelvic cramps?

I started having lower pelvic (which feels like gas) cramps about a week ago. Since then, I began having itchiness "down there" I would assume its a yeast infection, but Ive never had cramping too. Any idea what this may be? I am hesitant to buy yeast infection meds if its something that I need to go to doc about. Ive already had my period so it couldnt be that. I have suspected my husband cheating so I hope its not an STD! :( Please help! I think Im going to doc tomorrow, but want some opinions. Thanks!