I think my friend is lying about being anorexic? Help!

She has said that's she's anorexic and said she even had to go to the hospital because she stopped eating. However, she is now saying that she has really long periods with really bad cramps as bad as birth.

I thought anorexia caused irregular or lack of periods, not long ones you get for half the month?

she's lied about things before, and I don't know if I should believe her. Obviously, it would be terrible if I didn't believe her when she wasn't lying. But I'm really offended and hurt that she might be lying, my sister had anorexia and it's not something to lie about to get attention. It's a serious disease.

What should I do??