After maybe 6 months to a year of taking the
hydromorphone you probably could then get a prescription for
fentanyl if you still needed/wanted it since by then your body would be opiate tolerant. BTW, hydromorphone won't cause rebound headaches so you don't have to worry about taking it daily, it is an extremely clean medication with an extremely low side-effect profile and, as far as opiates go it has a very low-dependency profile.
Let me know how it all goes and how it all turns out!