I know how uncomfortable recurring yeast infections can be, ! I am sorry you are dealing with them right now.
Neither MS nor Ocrevus should be the root cause of the infection. That said, if you have made significant dietary changes or are on any antibiotics, or steroids to treat inflammation right now, they could be the problem. And, there's always a chance that another medication has messed with your body's natural bacterium and created an environment conducive to yeast overgrowth. Since MS can weaken one's immune system, that can also increase your risk of developing yeast infections, but that seems to be fairly rare, as far as I can find in my research.
Have you mentioned this to your doctor or gynecologist? Your doctor should be able to prescribe a treatment (or suggest an over-the-counter treatment) and, more importantly, offer some suggestions to end the cycle of recurring infection.
Good luck and I hope you get some relief very soon!
Best, Erin, MultipleSclerosis.net Team Member.