Except that today, two days after my period, I realized that there was a significant amount of blood in my urine. So I went to see a doctor and got diagnosed with a urinary tract infection. And now I'm starting to doubt that the Mooncup was the problem. I think I may have been having trouble urinating four days ago, but blamed it on my cup being positioned wrong. I thought my cup was leaking every time I peed. In the past, when my cup was full, it would usually leak when I peed, presumably because it was getting squished. But now I'm starting to think that there was actually blood in my urine for the past few days and I mistook it for menstrual blood.
I'm kind of glad to think that it may not have been my cup that was bothering me, though I'm hoping the cup usage isn't a contributing factor to the UTI.