Pharmacist mucked my scripts up, help?!?

Okay well first off i am on Lovan (fluoxetine) and i went to get my monthly script filled so i could get some more of them, the lady came over and asked if we wanted the cheaper version and we said yes because we didnt have much money for that week, but ive been taking them for a few days and i feel SO SO SO bad its not even funny!, i looked at the thing and it said cephalexin 500mg capsules and that i was supposed to take 4 a day, im like thats not right i was only on one a day before on my lovan!, so i went into google and it says cephalexin is an ANTI BIOTIC that came as news to me, so are Cephalexin 500mg capsules anti depresants or anti BIOTICS? and if she really did muck it up, what form of action do i take against the pharmacy?