I hope you have been reading the Healing Library. It is very helpful.
Your emotions are going to be all over the place. How is your WH behaving? Is he NC with the OW? Is he completely transparent with you? Is he patiently answering your questions?
You know, you can go to Planned Parenthood and get all your screening done if you are too embarrassed to see your regular OB/GYn.
Trust me, they see EVERYTHING there, they know all the tests to run. Then, if you do test positive for anything treatable, they can prescribe the medication. You can take the lab results for anything more "permanent" to your regular doctor.
Your WH needs to go in and be tested too.
Also, you need to go in a get tested for HPV. There is no test for men, just women.
Don't have unprotected sex until you both come back clean at least 6 months AFTER his last contact with OW. The doctor will tell you when you need to come back for rechecks.
IF your WH gives you any grief about getting tested, claiming OW wouldn't have anything and she can be trusted. Just point out that NO. She can NOT be trusted. She is a known liar.
Also point out to him that it is unlikely he is the only man she was sleeping with. It's not like he has a magic penis she couldn't keep away from.