hmm i used to get something kinda similar.. like.. id be on the way up.. just kinda mellow.. for 10 mins or so.. then i suddenly start feeling all dizzy.. and i'd start looking round in panic.. like.. my eyes would just be darting around the room non-stop.. and it'd get faster and i'd get all light headed and really sick.. it REALLY put me off.. but.. i decided to keep smoking through it.. few sessions later it was all cool again