Evil, Evil Semen and My Sweet Diva Cup

I've been using my Diva Cup for about a year now. Three months ago, I was smitten. It worked perfectly, it felt great, it was convenient, clean, healthy for my vagina, healthy for the earth, all that. At the end of my cycle, the cup smelled a little earthy, mineral-y and not at all unpleasant. I would boil it and it was good to go for the next round. I couldn't find a downside. But then I got a new boyfriend and we started having sex without condoms. 

I first noticed a problem when I put my cup in (after sex and after peeing directly after the sex) and left it there for the 24 hours that normally works for me. I've never had a problem leaving it in this long. When I took it out it smelled disgusting. Like cheesy, rotting, gross. So I boiled it with baking soda and got it ready for next time. I think at that time I was at the end of my cycle so I didn't put it back in. What followed was 2 weeks of a UTI followed by a yeast infection and just overall uncomfortableness in the area. So I realized that wasn't a good idea. For the next two periods I wait about ten minutes for initial leakage, which I then wipe up. I also make sure to pee. Then I pop the cup in. Two hours later I take it out and rinse, and again two hours after that. Then I change it every twelve hours, if it is that long before I have sex again - otherwise I just repeat the two hour cycle. 

The last two cycles I've had hints of UTIs which have been easily quashed with large amounts of cranberry juice. But there's also been a bad smell both in the cup and in my vagina. This time around the smell of the cup was so bad (like a particular Danish cheese that I love to eat, not to have inside my girlparts) that I just used pads for the rest of my cycle, as that was all I had. And my vagina just sort of constantly smells like I haven't washed it in 3 days, even right after a shower. 

Am I allergic to sperm? Did I have an STD? Have I just had three unlucky coincidences? I love my cup so much and I don't want to give her up but this isn't any fun!