If you do not hold domicile of Goa, you need to apply through All India Quota. All India Quota means 15% of MBBS seats in all Government Medical Colleges are pooled and filled in through a centralised Counselling system. So in other words, 15% of people who study are like you, not from Goa, do not speak the native language and are changing States and so you are not alone. Goa speaks English and so that shouldn't be an issue at all. And at all times, the medium of instruction shall remain English. There is nothing to be worried about. Things will eventually fall in place. It might take time to adjust to the new surroundings, culture and way of living but it is just a matter of time.