While it is illegal, medical schools tend to discriminate against older students. The fact that it take a long time (probably two years for basic undergraduate science courses assuming you have atg least some sort of undergraduate degreee, then four years of medical school, then residency) makes them reluctant for a new student who won’t start professional life until retirement age.
Consider fields other than a MD (RN is the professional that requires the least time). PA a bit more.