Baby movement


So I’ve noticed my baby really isn’t moving much the last 3 days. I mean he barely moves normally but now it’s literally only 2 kicks in 24hrs. I get checked a lot because of this problem. And my OB and anyone doing the scan agree that he’s just not moving but it’s getting worse. They shake my belly (pretty hard) just to get him to turn during ultrasounds but I just keep hearing he’s a “calm baby”. I’m 38 weeks and a FTM. Can someone tell me why he’s not moving now? I have an appt tomorrow but I’m getting nervous. Thanks!