Sarah - off to the Docs ASAP. It sounds like an infection. Go get some antibiotics. I don't ever say that to anybody, but in this case it is a must. Good luck. It probably isn't an STD but we can still get them by other means, eg if he didn't wash his hands well enough, or we are not careful enough when we go to the loo, it may even be caused by the condom. Don't worry just get treated quickly.
You may have bacterial vaginosis, which is a nasty bacterial infection of the vagina and not necessarily anything to do with sex. Go to your gp who will take a swab and prescribe a course of antibiotics.
Please dont take offence at me saying this, and Im not making any insinuations here, but couples who indulge in 'alternative' penetration and swap between the two without changing the condom or washing thoroughly can have problems with this.
Have you taken antibiotics lately. It could be thrush which is treatable with stuff you can buy over the counter at the pharmacy, but best to get it checked out by the doctor - just in case.