Medicine Entrance Exam

First of all, you have not mentioned complete information. So it is difficult for me to predict the accurate result because prediction depends on many factors like domicile, etc. However, according to your information, you did not get admission into any colleges in Karnataka. For more details, you may visit the Shiksha NEET college predictor tool. (https://www.shiksha.com/medicine-and-health-sciences/neet-college-predictor). I hope this will help you.

There is no college which provide B.A.M.S course with your score. For this course, you have to score more to get B.A. M. S.

If you change your caste from general to obc then you have to submit the obc Certificate or in correction time you may correct your caste from obc to general.

Yes, you can get BAMS course at a government college.

Not possible to any AIIMS or any medical college. You can apply for the next NEET and get a better rank.

Not possible to any college in medical course.

Probability is quite low.

The admission criteria for admission into B.A. MS is NEET UG and you have to qualify the NEET exam with at least min. Qualifying percentile :
For NEET 2020, 2021, 2022 the cut off marks and min. Qualifying percentile for SC category are :-For 2020 - min. 40 percentile and cut off marks 146 -113
For 2021 - min. 40 percentile and cut off marks 610 - 81
For 2022 - min. 40 percentile and cut off marks 116 -93
Thus, there are chances that you can easily get admission in B.A. MS with 169 mark in NEET.

Yes, you need a gap Certificate for NEET. A gap year Certificate is required for the dropper students who took a drop of a year or more after their 12th grade to prepare for NEET and are willing to take admission into colleges.

Basically 2 years for NEET preparation. 11th and 12th standard in Biology group. After that if you want more time for preparation then you can do drop for one year two year it's depends on you. You are able to do that and also you are able to attempt NEET exam more than one time.