I'm guessing you have a private loan--was this a consolidation loan with DRB or one of the other private consolidation loan companies? Or just medical school loans taken out through Wells Fargo, etc.? For private loans everything is up to your lender, and others' experiences aren't too relevant because they may have different loans from different lenders. Look at the terms on your MPN--I'm not sure I ever saw mention of fellowships with my 1 or 2 Wells Fargo MedCap loans. I also think they only gave a max of 3 years of forbearance, because if I recall I would've started repayments this past June (I consolidated my private loans with DRB and now get the $100 in-residency payments until 6 months after finishing residency).
If it's a private loan then your options are:
1) Start repayment (could be tough depending on your repayment terms)
2) Try to convince them to defer payments further (this rarely works, but if you can prove economic hardship it may--or maybe you can get reduced payments)
3) Apply for a consolidation loan with DRB and include the date of when you will be finishing your fellowship so you qualify for reduced $100 monthly payments until after graduating.
If you're talking about federal loans, there is almost no reason to not be on REPAYE unless you have a family and live in NYC or other extraneous circumstance.
