Basically Character A needs an illness that wouldn't manifest itself in any way that would send her to the doctors until it's far too late. I want around a 2 month life expectancy from diagnosis to the end (which as far as I can tell, should be relatively 'easy' since life expectancy varies so much from person to person) but for those 2 months she needs to have a fair degree of activity. She's a drummer, and I need her to be able to play for most of that period (her band are writing their second album, and she needs to be able to participate). She doesn't however need to be able to play well, they never record her parts, she just needs to be able to play well enough to transmit her ideas to the rest of her band.
My initial idea was a brain tumor, the symptoms of headaches and nausea are pretty maskable by a lifestyle of lots of drinking and partying. I'm not sure though, having looked up the symptoms, it seems like quite a lot of them might get a bit in the way of my aims for her, plus I don't want to overlook a illness that'd be a far better fit simply because I have no knowlege of it and it didn't pop up in google.
So basically I need an illness that would be suddenly diagnosed in a 22 year old female that would give her a life expectancy of around 2 months but still allow her to play drums for most of that period. The initial diagnosis doesn't have to acknowlege the short life expectancy, e.g. have high hopes for potential treatment until the condition is fully understood, in fact, it would probably be helpful.
Things I have searched: I've looked through most of the things that come up when you google brain tumor symptoms, and through the types of brain tumors, googled 'list of terminal illnesses' in various combinations, and 'types of cancer' and put the types of symptoms I'm thinking into WebMD to see if anything popped up.