me. I hv been requested for medicals checkup 3 times. BUt I suppose you should know what is the problem as the dr will tell. u. My case is my father has TB before but had been cured for many years ago. However, the x-ray film showed that part of the lung tissue was distorted. I then submitted all the medical treatment records from my home country (30 years ago) so that can speed up the process. However, they still need to monitor and disregard all the records. They requested to take x-ray after 3-month. Then we kept waiting and took x-ray after 3-month. The dr said usually 3-m is fine. However, they requested a further test, we need to wait another 3-m (total 6-m) to compare the x-ray film. Finally, they checked it is no difference and the medical finally passed in Apr.
So do ask your dr what is the problem and how you can meet their requirement.