Hey Aspirant !
Yes, Medical Certificate is one of the most important documents which forms a part of Document Verification during Counselling Procedure of NEET.
You need to get yourself thoroughly checked by a registered doctor and if needed, perform the tests like X-Ray, CBC etc.
To be precise, the doctor though whom you are getting yourself checked must have a valid Registration Number and stamp-pad which he must put on the Medical Certificate Form.

Hope this helps.

Best Wishes !