I was throwing up last night, and still feel really poorly because I didn't get any rest and?

I have an appointment later at the doctors for something else which is fine but I was not expecting to be so ill last night. You have to give the doctors surgery enough notice to cancel the appointment and I have not done that. I am struggling to stand up because I am feeling weak and it makes me feel like I want to be sick again. I am afraid if I go to the surgery that I will throw up there and don't know how I will manage to walk there. What should I do?