Hello,
If i go by the previous year record then your chances of getting admission in any of the aiims institute are low.
Last year the last merit rank admitted  for an sc candidate was 18049 in all india institute of medical science ,rishikesh.
The cutoff changes almost every year,so nothing can be predicted much.cutoff depends on the difficulty level of the paper and the number of students who appeared for the entrance exam.
Just hope for the best
Browse the link given below for better information.
http://www.medicine.careers360.com/articles/aiims-mbbs-cut-off/amp
Good luck

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