<p>Hey!
I don’t want to sound very pessimistic but I believe it is virtually impossible for you to change careers right now.
The AIPMT has an eligibility age of 19 years and you would be around 21 I guess. However, there is a provision for ST candidates- they can appear till the age of 25.
Assuming you can appear for the AIPMT- the competition is very severe and you are going to have to brush up on your high school PCB and maybe join a coaching class.
If you are serious about going for medical training, try a MBBS in China or Russia and then maybe do a MS/MD in India because those exams have no age barriers.
Your age shouldn’t be a problem- in a class of 200, every college has those 5-10 students who fall back every year… 
they fit in… you are a NEW student… you most definitely will
Best of luck!!</p>