I've googled 'tuberculosis symptom progression', 'viral symptom progression' (and I did find some things there but apparently TB doesn't fit the same patterns) and various combinations of 'tuberculosis' 'symptoms' 'time frame' etc.
Also, can anyone think of any diseases which are known for not being noticed until it's too late to treat? Or that are notoriously hard to treat? I'm mostly focusing on the lungs, but everything helps.
Edit: The character does not have access to modern medicine or anyone with more than basic first-aid knowledge. :3