If u applied to donate before and the medicine you were taking prevented u from donationg and your medicines have changged can younjust go in and reapply or do u need something from your doctor?

The answer to this question is entirely circumstantial. Due to the question being medical by nature, calling the center would likely not be very helpful. I would recommend you speak to their medical staff and figure out what you can do to get donating.

You can go in and try again, but you may need to have stopped taking the medication for a certain period of time. It depends on the medicine. You can try calling and asking.