I am having terrible anxiety attacks in the middle of the night? How can I make them stop?

Recently I have been waking up fine but when I try to fall back a sleep I have terrible anxiety attacks and cannot fall a sleep for anything. I close my eyes and just as I'm about to drift off to sleep I feel terribly anxious and find myself gasping for air and shooting up to a sitting position. I recently had a baby and this is who I wake up at night. I wake up to feed him, he goes right back to sleep and then when I try to go back to sleep this happens and can go on for hours. I don't know if it is worth mentioning but I am taking percocet with acitometophen 4 times daily as well as celebrex once a day for a bad back injury I sustained in December. Why do you think this is happening please help I am exhausted. Thankyou