Medication critic!!

Went to see my doctors the other day for CONSTANT vomitting, and he prescribed me phenergan. Dropped it at cvs, they gave me promethazine 25mg. I took my first pill(only one!) this morning at 8 AM, and passed out till 3:00 PM... I am now skeptical about taking any more. Helped with my vomitting but f*d me up pretty bad... Opinions!?