Ive had the exact same experiences. I use to be the type of person that wanted the strongest weed available so I get fucked up.. have a laughing fit, and pass out.. then wake up and eat twice my body weight lol. I was just one of those dudes that liked to smoke and get high and think everything was funny. Then it happened. I was chillin by myself in my garage, just hangin out. My neighbor came by and said if I wanted to smoke some shit he just got from the dispensary.. I said fsho man fuck it. Long story short we smoked.. he left to run some errands and left me chillin there HIGH AF!! Idk what happened but the feelings the weed was giving me started to feel like they were bad. Strange sensations in my head lead to thoughts of aneurysm.. chest feelings lead to thoughts of heart attack. I was scared shitless. Then the thoughts about being blind or deaf came.. they were so real I had to run to my neighbors house and go in so I would have somebody to talk to. I felt like I was dying. The anxiety and panic was so severe. I was feeling all negative feelings possible. After that episode I realized the anxiety was from me slowly slipping into a depression. My life was pretty shitty at the time. I had several more episodes like this before I decided to stop smoking altogether. I got sad because I would think about the first time I got amazingly high off medicinal weed and needed my cousins help to walk to the door. I just couldnt enjoy weed anymore. Anywho I stopped smoking weed for about a year. Eventually, about 2 years ago, I started slowly smoking again. One hit led to 2, and eventually I found myself going to buy a $20 sack every weekend when I got off work. Now, im able to smoke again and enjoy it. The euphoric feeling from weed that I used to get is long gone, never to return, but at least I can smoke some bud without begging the nearest person to call 911.
Moral of the story?
Its all in your head. I learned that the hard way and I hope before anyone else experiences those attacks they go into the situation knowing that it is all in their head.. your not dying, nothing bad is happening.