Hello, 

In my opinion let your son be a kid now. He would study for NEET when the time comes.

Let him explore all the possible paths that are there in front of him whether it's studies, sports, a tutor or anything and then truly decide whether medicine is a right choice or not. 

If he already is attracted towards science then he has found his answer. Ranks, marks and grades are of a prime importance because they decide your future admissions. With the existing loads of studies you will be burdening his life more adding preparations of medical entrance test. 

But above all this, if he is interested in medical then you must help him. Take care of his immune system as well and plan a daily routine. Never restrict him to go to play. 

I hope this is helpful. 

Good luck!!!