Is this a case of potential workplace discrimination?

Doctors suggested I seek medical treatment for what may have been cancer in 2 different locations of my brain. My employer denied me medical leave with or without pay although I was asking for 32 hours spread over four months. In no way would my having taken off impacted the employer because it would have been only a few hours every two weeks (up to 4 months). I was willing to work around my regular schedule to do it. I was told I would have to tough it out; earn every hour off with pay; and then if I was healthy enough to seek treatment, only after I had earned all the time off could I take paid medical leave I needed despite urgency. My employer said I was taking medical vacations (because I have preexisting medical conditions) & needed a new hobby instead of choosing to be sick. In contrast, a fellow employee (who is younger, healthier, and a different race) is consistently sick from work. She was recently out for approximately 3 weeks. Another younger, healthier employee has admitted she is "always in the hole" without hours, having taken a vacation overseas. The rules do not apply to everyone. I have to consistently clock in. They inconsistently clock in only when they want.