Recurrent panic symptoms and conditions

I started having panic attacks while taking Percocet. I am a chronic alcohol user, and I am saying this just in case it rings a bell for anyone. I have since stopped taking Percocet (about 3 days). I was a habitual/recreational user ... meaning that I took them when available, but I did not always have them. Since my last dose, I have been having recurrent panic attacks that are very scary. They include physical symptoms (heart pounding, cold and hot flashes, feeling of difficulty breathing, sweating, shaking) - and the much more scary mental symptoms (fear of death, walls closing in, inability to think or concentrate, vivid dreaming, fear of people, etc.). It appears that some other people have had issues like this, but not everyone. Can someone share their story with me. Has anyone had similar experiences ? Do they go away at some point ? Is it withdraw (I am not sure since they started while I was using them - but continued after I stopped) ? I have heard that it just takes some time, but it is very scary. I get some relief by drinking ... in fact almost complete freedom from most of the symptoms, but I can't just drink all day. Please help.