Weird feeling

It's been nearly 4 months having my little boy, and I've been with my partner 2 years, we have unprotected sex and I was on the pill but decided to stop as I had a clot the length of a pencil, I'm always taking pregnancy tests just to be sure but lately I'm feeling like little quickening movements as if I am pregnant, I have a Doppler I use to check but there isn't anything that can be heard, and like I can't seem to lay on my tummy anymore either or lean as it hurts to much now :/ anybody know what can be wrong or what's up, I'm not pregnant because my Doppler can't find a heartbeat and I take tests and they're always negative,but I look 2 1/2 months gone x