Diva cup sitting to low, wasn't before

I bought a diva cup about a year ago because I was sick and tired of dealing with tampons, i liked the suction, and they sell them at harris teeter. I loved it. Seriously, it was so comfortable i couldn't even feel it, I had no issues with insertion or removal. Then one night, because I couldn't feel it, I forgot to take it out and empty it and it stayed in there for about 20 hours before I remembered. Gross. Anyway, so that was a nightmare because it had shifted up and removal was one of the most exhausting and terrifying processes of my life (no joke). After that, I noticed removal was really difficult. I had gotten a giant box of free tampons from a friend, so for the past few months, I've used those. This month I ran out of those free tampons and I have tried to use my diva cup again. This time, however, it's sitting far too low. When I do manage to get it in a comfortable place, it falls down. It's very painful. It was never like this before, in fact, I had the opposite problem there for a while! I'm wondering if anyone's had this issue and what I could do about it. I don't think my cervix was like "you know what, I'm going to get lower in your vagina" and dropped. I don't think the cup was like "you know what, I'm going to grow" and got bigger. And I don't feel like I just *forgot* how to insert it, considering I did it successfully for about 9 months. Help?