Shitty co-worker

I was told by a co-worker that my agoraphobia was laziness and that a long standing health problem was just me getting out of work. I do way more than most the people at my job and it pisses me off to be treated like this. This is just a co-worker not management but I'm afraid that I'm going to get fired eventually cause of my problems. I've been out for almost a week throwing up everyday and I dont want to go back cause I don't want to get shit for being sick