I think we have had this in another post a few months back.
I have the same problem but im not looking at it as a problem because like Bex said some people are idiots and its you you have to worry about not their stupid attitudes.
When im feeling ill and i have social occassions to go to, i get all the attention, everyone talks to me,(they dont know im ill) and im really part of the social scene but im not making much effort but if im feeling okay, i get ignored but i think it might be because were sensetive more to our surroundings and peoples feelings when were not focusing on how ill we feel at that time, this is my conclusion.