Emril,

It is extremely difficult to get into a US medical school even for people who were born and raised here. It will be much more difficult for someone coming from Nigeria, but it is possible.

I don't know how much education you received to be a physical therapist in Nigeria. I'm not even familiar with the educational requirements for physical therapists in the United States, but I believe they typically have a 4 year college degree. Assuming you have a college degree from Nigeria, I would guess it would virtually impossible to get accepted into a US medical school directly. Perhaps if you knew someone connected to one of the medical schools, it might help, but otherwise, I doubt a medical school admission's committee is going to want to try to figure out whether your college in Nigeria is any good. There are multiple applicants from top US colleges for each medical school spot already.

I know very little about immigration law but from what I have read, if you have a green card (non-US citizen permanent resident) then you are generally treated the same as a US citizen. You can qualify as a legal resident of a state and would be given the same preference that US residents of that state would receive at public and some private medical schools. If you do not have a green card, most medical schools will not even consider your application. There are maybe 50 out of 125 medical schools that would consider non-green card holders. Of those schools who will consider your application, they likely will have extra requirements since you would likely not be eligible for federal financial aid. They may make you prove that you can afford the financial obligations of the 4 years of medical school. There may be other types of funding available, but again, I assume this type of funding would be extremely competitive. If you do have a genuine interest in research, you can consider an MD/PhD route, as medical schools may have more willingness to accept a great candidate for one of those spots.

It would seem to me the best chances of getting into a US medical school would involved getting a green card in the US and taking the required pre-med courses at a college in the US. See the thread on medical school requirements for a better understanding of what the typical college requirements would be. You would need to do extremely well in those courses and then take the MCAT exam and do well with that. Then you would follow the application process to a US medical school.

Medical school is four very challenging years. After medical school, you would need to complete a residency program. You do get paid a relatively small salary while in residency, but at least you are no longer paying for your education. Residency programs are anywhere from 3 years to 5 or 6 years. Some doctors choose to do a fellowship following residency for more in depth training.

Overall, for a US resident, the whole process takes 4 years of college, 4 years of medical school, and at least 3 years of residency.

If you have more specific questions, feel free to ask.

I want to know is how i can transfer to the US medical school from an indian medical school to do the internship/housemenship program

Unfortunately, I don't know much more than I did when I made this post in reply to a question about transferring from an India medical school to the US. You can follow the link in that post and maybe it is helpful, but I'm just not familiar enough on this topic to be of much help. If anyone else knows, they will hopefully post in the other thread.