wow, i actually have had a couple experiences just like this in the last couple months, i took 15 hits once with a friend and kept on thinking i was gonna die and all that and then did it again later and was shaking and stuff, i've quit for awhile (3 weeks and im going to go until march i think) i dont know what im doing wrong, it could be im dehydrated or something but the last thing you wanna do is be nervous if you decide to smoke, it makes the weed act faster i think and can really screw you up