Singlewedge

First question I have is this.

Was the cocaine cut with anything?

It sounds like the cocaine was laced with something nasty. You mention facial, nasal, and head problems. Cocaine is a numbing agent and the purpose of snorting it is to bypass the blood/brain barrier quickly.

Perhaps this has affected the blood/brain barrier in some way. The jerks could be from some kind of neurological defect as a result of the cocaine and or what it was cut with.

If you have any left, which I doubt, you could have that tested. If you know the guy you bought it from you could ask him/her they may know.

Not sure about the other symptoms but I would ask your doc about the blood/brain barrier and see if there is a test that might point to something wrong there.