get a lawyer. if that went down just like you said it did its an illegal search and seizure. with as many people were at a college event there is no way he can say it was you that smelled of pot.
i am hoping you remained silent and did not give him permission to search you when they asked.
do not talk to the police without a lawyer present .. say nothing
execute your right to remain silent.
execute your right to a lawyer.
and even if you did snitch you will still be fucked ... cops lie.
lawyer up and get it tossed out