How to Add Time Constraints with Magic/Curses?

I've got a plot. The protagonist's mom has been cursed by a fae, and it's up to the protagonist to cure her. However, there's one problem that affects both myself and the protagonist. The problem is that magic is not currently practiced by humans, and the closest race of mages is a very long journey away.

I want to put a time crunch of sorts on my protagonist. Something like "No one who's ever been cursed by the fae has lived for longer than six months afterwards." However, this situation 1) does not exclude the possibility that the mom can die before those six months are up, and 2) requires a character who knows a lot about fae curses, which I don't have. Originally, I was going to have the mother be pregnant. The only human character who knows anything about the fae would give the educated guess that the mother could keep herself alive long enough to give her child a fighting chance at life before dying in childbirth. However, I felt that this situation was too dramatic/implausible so I cut it.

How do you manage timelines with curses and magic? Any advice?