sawfoot _:
http://en.wikipedia.org/wiki/Afterimage
The weird visual stuff sounds just like visual after effects to me - I find sometimes if I shut my eyes and focus on the after image of a bright light it can do all sorts of weird and funny stuff.
Did you get rushes of excitement or tingles of pleasure? Or feel high?
Yes, after the sense of relief I felt quite blissful and happy. Almost mild euphoria, not quite high.