Interesting plot! Me gusta your idea. ;3 Here are some suggestions, of course, you don't have to go by it. I'm not considered really a "creative person". You did the work you get the credit.
But I think witches are too mainstream...maybe you should try something else, like the idea you have. I don't think you should make it with "witches" and "scientists". Don't do what most stories with a curse do. Use your imagination. Like unicorns sent the curse. (No, don't do that.) Maybe a creature or something.
Naming the curse is the hardest part. How about they don't know it yet, but later in the story they find out?
When the main character finds out about the curse, how about there is this old man sitting on a log by the fire in the dark? The main character sits down when the man invites him, and then they talk. After the man introduces the curse, he suddenly disappears when the character looks away?
That's all I can think of. Sorry if this isn't much of a help - I used to write stories but now I don't. I'm horrible with expressing human characters, but better with animals.
Good luck on your story, and I hope you find something suitable for it! <3