Incomplete prolapsed uterus?

Just some background: I had a vaginal birth 11/13/19 aaaand only suffered a first degree tear. Everything healed quickly and my husband and I have been having great sex since my 6 week post partum check up and I had an IUD inserted. For the last week and a half we've been extra horny for each other so literally once a day if not twice a day we've been having amazing sex. I noticed a couple weeks ago I could not feel my IUD strings, my OBGYN said they could check them, but if I wasnt having bleeding or cramping, they doubted it was out of place.

Anyway, today I went to check again and I feel this spongey almost mass thing like thing thats not normally there. I am very familiar with my vagina so I know when something doesnt feel normal. Not sure if I'm just a little swollen from all of the sex? I've been very wet every time though and it doesnt hurt.

Im going to contact my OBGYN tomorrow but I'm starting to wonder if it's a partial uterine prolapse? Has anyone had one or can shed some light on it?