Should I tell people that my suitemate is probably making up her illnesses for attention
Why do you want to tell people that?
For the sake of truth? Isn't that what you guys do?
It can be hard to understand what people feel sometimes but it is not good to think they are lying and it is not good to tell other people that. People will think you are a busybody.
Who cares what they think, she's probably lying.
Not all illnesses have visible symptoms. You should respect her and maybe do some research about the condition before you make a fool of yourself.