Worried

So I have a Doppler and for days I was able to find baby's heartbeat, but before I had my appointment Friday I couldn't find it, the doctor couldn't find it with a Doppler either, but they found baby on an ultrasound however higher up than they thought... At any rate since then I haven't been able to find my baby's heartbeat?! I'm guessing I just can't hear it through the ring of fat and due to the fact that he's higher up, but I'm starting to worry! Any thoughts? Maybe I should just put the Doppler away for awhile.