Also, a couple months before the panic attack while driving, i had a panic attack after smoking weed and drinking. I got crossfaded, decided to drive. Pulled over after 5 min.. called friends. Got home and was freezing. Couldnt get warm even after a few hot showers. Heart racing, pale skin, nausia. Went to e.r. and they gave me a pill to calm me down. That was my first experience. I tried smoking a few months after and heart began to race again. I wont smoke anymore.
Two possibilities. One, there is something physiological going on which only a thorough exam by your doc can find. The second, and probably more likely, is that the panic attack you got while stoned released something that was inside you and now it's out. Many people get their first panic attacks while stoned. For most, it's one and done and they move on, but for some of us we then expect to get a panic attack when we feel similar to how we felt when we got the first one. For me it went from episodic only when I got high to chronic. It might be for you an anxiety attack disorder that was waiting to come out and now it's out. It's always good to get that exam, because a lot of things can cause anxiety -- thyroid problems, hormonal imbalances, hidden viruses, blood sugar problems, and so it's good to rule this stuff out as best you can. If nothing is found, then the next step would usually be a psychologist who specializes in anxiety treatment or some other modality to try to alter the patterns your thinking is taking -- if it's an anxiety problem it's the anxious thinking causing the physiological symptoms -- and if that doesn't work and you're still having problems, then it's time for something else, either a natural medicine approach or a psychiatrist for medication. Given you're still functioning pretty well most of the time, I'd try to fix it without meds if you can, as they are, well, meds. But it's time to try something, because the longer it goes on, the more panic attacks you have, the harder it gets to fix.