How large is the company? Is there a human resources dept?
Can you talk privately & confidentially with your boss about this?

they could be just rude people or they might be trying to squeeze you out...

I'd be sure the boss or HR dept, has the relevant medical info needed and is kept up to date with your problems getting dx'd, unless he is untrustworthy??

If it feels like you are getting singled out because of your illness you might need to contact someone or read up on discrimination, to see if it that applies and who to contact about it.