The short way of me tryng to help:
You assimilated studing to pain, you need to find out why, and reverse it.
The long way:
You need to find the purpose of why you are shooting to become a doctor, This is nothing like IT, where if you make a mistake you can always redo the hole thing, we will be dealing with lifes of fathers, sons mothers and daughters so you need to be 100% sure that this is what you want, not what something that someone planed for you. If you are lacking on motivations even if this is something that you really want, but you cant deal with the stress, go out, excisercise, and stay in touch with yourself. I went trhu all of Tonny Robins audio book and DVD, and that really gave me the push I needed to make the decision for medical school.
Im sorry if it was kind of hard to understand, my english still poor, but I hope it was of some use.
I wish you all the best to become the best 👍