Sometimes so Scared

When i used to smoke weed everything was fine, after a while it started to become a daily routine about 4-5 times a day. I'ts been about 11 years since i started, the past 3 years ive been experiencing very scary and ridiculous thoughts, sometimes so scared that im just going to drop to the floor and start convulsing. When the scared weird feeling starts to happen, i look around the room and everything just feels like its not real, and when trying to talk to someone i feel stupid and at a loss of words, figit alot and just feel like im not really there.
I use to be a very socially active person and friends with everybody, use to party with my friends and enjoy life. Since this started i have no social life at all, i spend all my time on the computer, i gave up caring about what i look like, ive even stop socializing with 2 of my sisters who have done nothing to me or anything wrong at all, i just lost total connection with them and the outside world. Im scared to meet new people ( even tho i say i dont have that problem ), im scared of what people think of me all the time, even on the internet which even to me seems dumb. I really think im losing my mind and there is nothing i can do about it and it will just keep getting worse. I know thinkin negatively is probably making it worse but its another feeling i cant control. It's worse when i smoke marijuana so i have cuz that back to once a day and even now when i only smoke it once i get these feelings. They are starting to happen without smoking marijuana now so i think i messed something up in my head by smoking pot. Im going to stop smoking completely and waite for a few months see what happens but im really scared. sorry about long post