I think I've had some mild anxiety attacks before when high. Nothing too serious, but basically my thoughts would run wild, but in a bad way where I wasn't even comfortable with my own thoughts, and it would bring on a sense of paranoia. I think the best remedy to this is to let something else occupy your mind until you begin to feel better - just watch a film you like or put on some music and go into passive mode.
I ran out of papers last week, and first the first time in a long time I made a home-made bong for a quick fix until I can get more papers (local smoke shop closed down). Man, I got really high. It was awesome. Haven't felt like that for a while. When playing GTA V, I'd been to the shooting range before and enjoyed it, but I went back after getting lifted and it was super intense, and now the shooting range challenges are among my favorite activities in the entire game. It was then I was able to appreciate the improved shooting mechanics in V since I could really feel the weight of the weapon and its discharge. And I remember I started to think about how a gun is a really f*cked up piece of machinery and how awful it must be to get shot by one.
When my wife saw me preparing the bong, she said it looked like something an addict would do Of course, I told her that I'm not addicted, I just have a particularly high tolerance, let's not muddy the issue..