Drug overdose?????!!!!!!!!!!!?

Every morning, i take 2 pills that are kinda strong. one of them is a vitamin, and one is an allergy pill called allegra. After a few minutes of digesting them, I feel like im gonna puke. i get all dizzy and start tripping and falling all over the place! i don't know what is happening to me, cuz the doctor said its alright to take both at the same time, and to take them each morning. my parents think its the vitamin, but i need to take the vitamin to help keep my bones strong, since osteoperosis runs in the family. plz help!