Hey, 

Well it depends on you entirely. 

A score of 450 isnt bad at all. With lilttle more efforts you can get into a good government medical college. Even now you may try for collges in UP where theres no domicile. Maybe you can get into a good college there.

Regarding joining private college again it depends on you and your parents. The fees is obviously high there. So if you can afford you should join. 

Because taking a drop is beneficial if you can work with the same zeal and entusiasm. But if you take it as a set back then it will be in vain. So analyse your state of mind and take a decision. Do consult with your family. 

All the best.