Fiance thinks I'm acting strange because of irritation, why?

My fiance and I have been together over eight years. I've always had my yearly check ups, pap smears and STD screenings yearly. Two years into the relationship, I contract bacterial vaginosis. It is sexually transmitted. I've had the same partner which is him and I kept contracting bv for a few months and then it eventually went away with treatment. Now in March I had a reaction I thought was from Vagisil feminine powder because as soon as I stopped using the powder the irritation eased a bit. My fiance from the first week in March until May 8 had beenincarceratedd. My irritation started again in early May. Then it got so severe last week with all the itching and downright unbearable irritation. I told my fiance about it and now he thinks that I've been sleeping around, which I haven't and he thinks I have herpes. I just had a pap smear in March of this year and all was fine. I also had STD screen and no diseases. We would of had our first child together four years ago, but it was an ectopic and my left tube ruptured and I had to have emergency surgery. I don't know what to think but he makes me feel guilty when I haven't even done anything wrong. All I do is work, attend college and back home and maybe shop here and there but that's about it. and I told him about it I have had an STD in my past and told him this when we met. He also told me his sexual history which he said all he contracted was crabs. I don't know where all of this is coming from but it's upsetting me. I don't want to argue with him over this. I visit my dr very regularly. I bet she gets tired of seeing my face! Him on the other hand doesn't go to the dr at all unless it's an emergency. I just don't know? I need some advice on how to handle him when he tries to twist things to make it seem like I'm the one in the wrong about things and I get to feeling like I have to defend myself when I know I've done nothing wrong.