Nervous. 😩

So I'm 20 weeks and 3 days pregnant.. I've been feeling the baby move every now and then for a few weeks but now it's like all of a sudden I can't feel anything. I've not felt anything for a couple days... I'm beginning to get very scared and nervous about this. Am I freaking out for no reason or should I call my doctor and get an ultrasound to check the baby out?!