I'll offer a recommendation: tomorrow, check in with your immediate chain of command to confirm the process to report a change in medical status including notifying DODMERB and/or your unit as needed. Certainly do not disclose your medical specifics to anyone - that's protected data/ private. Why would I not wait? Because you
may be required within 72 hours (or whatever the deadline is) to not only notify your unit, but file your change in status with DODMERB - I don't know how this works with Army. Do you have a regulations manual that clarifies which official
form(s) you need and the process to do so? Ex. DD-Form 2372, DD-2807-1? Recommend you confirm the reporting procedure within your unit.
If you're an MSIII then you're not new to ROTC, and for most questions you would be killing a moquito with a bazooka to engage with the PMS to get process questions answered - often, others can help. I do understand for the actual diagnosis details you want to keep that as sensitive and perhaps PMS or your medical officer only - of course, protect that data - you should - I'm just suggesting you not conflate the process question with the actual processing/ adjudication of your specific situation - and, hustle on this tomorrow so you don't run out of time to be in compliance.
Good luck to you.