I've had this in the past...it seems to come and go for me. It started by me isolating for long periods of time, then I would develop a very real and intense fear of leaving the house at all.
What worked for me is taking it slow..."forcing" myself out, but not expecting too much. Like maybe a walk around the block; maybe going to the grocery store and giving myself permission to walk out without buying anything if the fear and panic got really bad.
Be patient with yourself and don't overdo it, but if you stay in it will only get worse.