A swelling tongue can be a very distressing symptom that should be evaluated by a doctor
right away. Depending on its severity and your ability to breath without problems, you should either go to the emergency room (if you are having trouble breathing) or see your doctor as soon as possible (if your breathing is fine). The best type of doctor to see for this is a primary care physician
such as a family doctor
A swollen tongue can have a few different causes. The most severe and life threatening is a condition called angioedema. This is where fluid leaks into the tissues causing swelling. Symptoms besides a swollen tongue include swelling in the hands, arms, legs, face, and throat. All though I can not be sure, it seems that your description of feeling "fat" may be consistent with the. Causes of angioedema include severe allergic reactions and side effects of medications. It is usually very fast and thus, your description of it going on for a week is not typical.
Other causes of a swollen tongue include vitamin B 12 or folic acid deficiency. These would be very unusual in someone your age unless you were a strict vegan.
I suggest you get seen by a doctor soon. After a good history and physical exam, your doctor will be able to tell why your tongue is swollen.