Hello Dr. Ranjit, Greetings!

So what I think is that the correction of the DOB should have been done way before hand. Also now, if there are any chances of making the corrections before the deadline of NEET application, just go for it. Secondly, there is no DOB written on the marksheet . That is the 'Secondary School Certificate' on which the DOB is mentioned. NEET applications use that for your DOB proof and sometimes give you alternatives for that such as your birth certificate.

Hope this answer helps you.

Feel free to ask any more queries that trouble you.