Is my job is making me ill...?

basically, I'm working in a factory, 9 hours a day, 12 days in a row with only 2 days off before doing the whole process again. on top of that me and my colleagues were pretty much forced into doing an hours overtime today... Is that even legal? I'm feeling completely drained, like I don't want to get up in the morning every day and I'm constantly aching. I was told last week that because I went to the doctor (who told me he suspects I've got a brain tumour) and had 3 days off sick, I'm not allowed another day sick til the end of june. I really feel like just not going back but I live on my own and obviously need the money. I have also enquired about less days to no avail. Can anyone help me out? I really need tomorrow off to go to the doctors but I don't want to lose my job.. Till I have another one lined up :(