I've suffered some similar symptoms as you have.
I sometimes think it may be our consumption of other substances that may contribute to something like this...
(i hope mention of other substances is ok in these forums, i've received warnings before for mentioning other things on other forums...but i feel that for the topic of this thread and feedback to sektorone that i may need to...so forgive me).

Personally, i consider myself fairly experienced smoker. I've been smoking mj for about 7 years, nearly on a day to day basis for a lonnnnng while.

Mj has always been my favourite, but i've had substance abuse problems with several things in the past, namely e and crystal meth, which sprung from some personal issues i had to deal with.
There was a period of time in my life where i would drop 5-6 pills a day...and this considerably messed up my head big time in terms of memory, aphoria etc.
After this i stupidly messed with crystal for a bit. This is where the source of my paranoia lies. Crystal subtlely messes with your head, so subtlely that many heavy users suffer behavioural changes etc. Personally i foudn that when i smoke, everyday of the week after after a long session of using meth (3-5 days straight), i would be intensely paranoid during the entire high...
I've also used LSD on several occasions before, in high doses (7 blotter trips), and i dont think my paranoia stems from this...
I'm also a pack a day smoker, but i'm a pretty firm believer that nicotine relieves stress and anxiety, so im not sure if this is it either...

but i guess different chemicals affect people differently...my bane may have been meth...maybe yours is LSD...

imo if i were you, i would probably take a short break from any substances...then come back to it and see you feel

i really really hope you find the source and a solution to your problem. because quitting all together is a very sad sad thing indeed...
best of luck!:thumbsup: