Pending miscarriage?

I hope this isn’t inventive to anyone, I’m not sure what group would be the correct place to ask this.

I am 13weeks 6days.

2 nights ago I started bleeding after sex.

I read that that could happen so I tried not to worry, it wasn’t period like but enough I needed a pad. It continued off and on all day with dull back cramps and yesterday evening I was having sharp cramping to where I needed to lay down.

This morning the cramps are dull and achey and the bleeding is light but still there.

My OB didn’t seem concerned yesterday and told me to just rest and that it’s normal after sex but I called again today wondering how long I should expect to keep bleeding and now they’re having me come in for an ultrasound.

I never bled In previous pregnancies so I’m worried. I want to be realistic and prepare myself.... I’m nervous.

Does this sound like the beginning of a miscarriage?

Thanks for your help!