Why did I get a panic attack after smoking Marijuana?

Hello doctor,

About a month ago, I decided to smoke marijuana with some friends, as I have several times before. Everything was going as usual, but when I took the second drag, I instantly had a panic attack. I decided to go to my room to try to wait it out, and after a while, the high went away, but the panic stayed. The rest of the night, I was in a state of constant anxiety, and at around 10 PM, I took some Doxylamine to try to fall asleep and end the night. When I woke up, to my surprise, I was still in a state of panic. This is where I started getting more worried. The rest of the week, I felt depersonalized, and I had horrible anxiety. I had several ups and downs during this period where I would feel better then worse and so on. A couple of weeks went by, and I slowly started feeling a little better. It is the fourth week now, and I still feel as though I have this pit in my stomach, which I am always trying to fight to prevent another full-blown panic attack. I feel horrible, and I just want to feel myself again. The Doxylamine seems to help calm me down a little, but this is not an ideal way to cope, as I cannot be tired all the time. Most of the time these days, I feel fine, but when I am not being proactive or doing something, I feel it creeping on, and I dread the feeling. I have been feeling depressed lately as a result of all of this, and I just do not feel the same. Did I inadvertently trigger some kind of panic disorder within myself, as a result of smoking? Or am I somehow over thinking everything? I want to go to my physician to talk to him about it, but he will probably think I am just trying to get my hands on Benzodiazepines or something. Any help would be grateful. I do not know how much longer I can live like this. Thank you.