Uterine spasms?

I had my IUD taken out on September 20th. So it’s only been a little over a week. We had sex for the first time since taking it out and everything seemed normal except today I’ve had the uterus spasms ALL day long. Not painful, just spasms. Almost like phantom kicks (I’ve had three babies so I know what it’s like). Anyways- why would I get these spasms? I’d be SHOCKED if I got pregnant. Of course anything can happen but I’m not sure. Any thoughts?