Hello Caucus. I have also been (mis?)diagnosed with PTSD and BPD, as well as many forms of anxiety and depression. I have been experiencing dissociation, depersonalization, and derealization for as long as I can recall, even as a very small child!
The tricky thing is there isn't any real way to call something dissociation. It's very subjective. It's hard to explain and tough to convey. And a lot of people, most people I'd venture to say, do experience all kinds of dissociation in mild forms at various times in their lives--it just doesn't negatively impact their lives as it does for those of us who seek out help. It's a coping mechanism of sorts.
I absolutely think that dissociation can feel like that. For me sometimes I get amnesia, sometimes not. Sometimes the mirror looks funny, or everything is dreamlike, or people seem fake, or I seem fake, and I want to claw out of my skin. Sometimes I just don't feel anything at all, I feel dead and numb! All very scary feelings. The disconnect from your body and mind can be terrifying. The time loss as well.
I also get philosophical sometimes, Caucus, during dissociation periods... so I can relate in that regard. I don't often, but when I do, my mind goes to scary places.
Clonazepam is something I have been on for over a decade (I'm in my mid 20s!!). I actually find the more often I take it the more I dissociate and more often with amnesia. Your mileage may vary. I am rx'd the clonazepam as needed so I can choose when I need it

.
I find it helpful to get a stone or object that I feel is grounding, or to massage my own feet, or do a few yoga poses. Taking a walk barefoot briefly can be VERY grounding, as can a deep tissue massage, hot bath, yard work, very hot tea, rubbing icy hot type products on sore parts (I use Max-Freeze from Wal-Mart which is cheaper AND WAY more effective... it grounds me and snaps me back into myself because it's very intense!!). Music can help too, as can dancing to that music. Writing about a specific topic/hobby/movie etc on a forum can also be grounding because it puts you in a different mode of thought yanking you out of that philosophical panicky mode of thought.
Hugs if you want them. I know how it is. I hope you feel better soon. Have you spoken with any professionals about all this? I am over email now and in person very soon.
-- Thu Aug 23, 2012 8:15 pm --
Wanted to add, I also CANNOT concentrate when I feel that way! I have slept it off before too, but usually I'll drink a Bob Marley's Mellow Mood thingie from the gas station or a valerian tea, several brands at the store have nice calming teas to ease me to sleep when I need to 'reset' the brain from that state!