I understand how you feel. I have experienced a similar depression.
First, do you truly want to be a doctor, or in the medical field? Have you been realizing this is not what you really want to do? Is it what you are expected to do? Do you feel trapped, like you cannot turn back and do something different?
Is it too much stress? Are you getting enough sleep? Some universities make a point of over-working the students, which is counterproductive, in my opinion. Sleep is critical for quality studies. Are you drinking a lot of coffee to keep yourself going? Caffeine can ultimately drain your body and cause depression. Careful with the sugar, also. I speak from experience.
If I had known about nutrition and food sensitivities during college, my Depression problems would have been MUCH easier to deal with. In addition to talking with a counsellor, I recommend getting tons of quality nutrition, daily sunlight, and daily exercise. Consider the possibility you may have developed food intolerances ...these can wreak havoc. Eliminate gluten for two weeks, it could make a HUGE difference in how you deal with stress. If you can, start juicing. Omega juicers are great. 16 ounces of green/ginger juice a day can really lift your spirits and make it easier to deal with what's going on.
This may sound crazy, but perhaps you can take a year off and go WOOFing? You can travel and work on organic farms, and learn about various farming practices, in exchange for work. You might find it refreshing. I wish I had done this.
Just wondering, perhaps the food in your home country was more nutritious? Is your university in a polluted place? Could there be toxic mold in your housing? All these things can amplify existing problems...or create them.
I'll check back to see if you write here again...I have *been there, done that* with debilitating depression, and I understand how terrible it is.