i'm working on a story and an inciting event i thought of was a character will get sick and is dying.
Necrotizing fasciitis. Google it, but not while eating lunch. Actually, a few weeks might be hella optimistic for that one.
Kidney or liver failure, due to heavy drinking and/or drug use.
'drew, kick it old school with the Bubonic Plague - the Black Death. Catchy name, right? After a sold-out performance in Vegas, your adventurous young rocker decides to head to the desert to do some risky rock climbing. Along the way, he stops to help a dehydrated dog, little know it was in a scrap with prairie dog - and prairie dogs carry the plague. The dog is mad, and it nips the rocker. He thinks nothing of it, does his rock climbing thing, but soon the first hints of the Black Death start to appear. Use it. No charge.
Check out fatal diseases online.
Cholera, Malaria, Yellow fever, Diptheria, Black death, Anthrax, Smallpox, Meningitis, typhoid.
Someone I knew died less than a month after being diagnosed with cancer.
That brain eating amoeba is one. Death in about 7 days after symptoms show. Rabies is fatal, once symptoms show. (You can prevent rabies, but once it's in full bloom, there's no cure.) Brain cancer can kill you in about 7 - 14 days once the massive headaches start (again, rarely detected until it is too late.)
The Curse of Lord Bubo is an ancient disease originating in Medieval Africa. Legend has it the Lord Bubo's wife cursed him will a warting disease so she could elope with another man. The Curse is now a relatively unknown STD often found amongst prostitutes. It's very deadly, capable of killing the inflicted in a matter of days by clogging the bloodstream with warts.
Be specific. Even something as benign as the flu can kill the very young, very old, or a physically strong adult with immunity issues.
Same with Pneumonia and bronchitis, things like that.
Use the Mayo Clinic website, they breakt hings down into all sorts of suggestions.
A drug overdose. Everyone will assume 'a young rebellious rockstar' died of that even if s/he didn't.
He thought he was eating "magic mushrooms, but stead, someone sold him something they picked from their yard. Symptoms of most mushroom poisonings are stomach problems and nausea, followed by a period where you feel better, followed by massive liver failure and death in a few days.
flesh eating bacteria.
I know Lou gehrig is fast but not weeks I dont think
A lot depends on the person your story needs to die. Is he or she a child, a young adult, and older adult? How's their health before this disease? Have they been vaccinated against the former killer diseases like measles, polio, etc.? And is your story set in present-day?
About 80 people die every day from pneumonia, but most are elderly. Influenza, too, is often fatal, but most commonly in people who had other health issues. Worldwide, people have more to fear from measles than ebola.
Without knowing anything beyond "character must die in a few weeks," I'd consider MRSA.
I believe rabies can also cancer can kill you in two weeks