Problem with this medicine?

Im taking this medicine called ic nortriptyline hcl. and i only took 2 pills so far and its my first time using it. Anyways i was about to get up to blow dry my hair when all of a sudden i blacked out and fell down the stairs. mind u that the bathroom is here upstairs and i wasnt goin downstairs i just dropped my brush i guess and was blackin out i remember rollin kinda but not much. do you think i could have the side efects on only takin 2 pills. its 25 mg.