Katie,
typically it is recommended that you give the antibiotics 2 full weeks to work and then, if there is no response, you should get a referal to an ENT. Sometime infections in the oral cavity can be difficult to treat. Infections can also cause the lymph glands to swell up and sometimes even be tender to the touch which is normal. We don't often see people here in your age group but you should push for that referal if you don't respond in the proper time frame for your own piece of mind. There are many other things it could be besides oral cancer. Peri-tonsillar abcess comes to mind and can take months of antiobiotic therapy. Please keep us up to date on whatever happens.