@SarahGen-- Yes, antibiotics can cause this type of rash. What type of antibiotic are you on? Did the rash start about a week after you started the antibiotics? Beta-lactam antibiotics are usually the culprit. If you're taking a penicillin group antibiotic, you can bet that that's the cause of the rash. These drug induced rashes usually don't show up right away. They take about a week to show up.
Do not stop taking anything before seeing your doctor about this. At least call him up right now and let him know about the rash. Although you should not use drugs that you have a sensitivity to, quitting antibiotics before treatment is over can worsen your infection and cause more complications. Your doctor will most likely switch you to a different group antibiotic that you are not sensitive to. Skin rash diagnosis requires tests and the doctor needs to see the rash. So see your doctor right away.