About a week ago my tongue swelled and then the taste buds fell off and eating or drinking burns and i can't taste anything. what could this be?

Many Possibilities: For a fairly complete list of possibilities, see http://www.Nlm.Nih.Gov/medlineplus/ency/article/003047.Htm . Sometimes the cause is unknown and the diagnosis is called burning tongue syndrome or idiopathic glossopyrosis. You will need to be assessed by a dentist and possibly referred to other specialists to get an accurate diagnosis.

Not sure: Sounds like an autoimmune problem. If you are on drugs, then steven-johnson syndrome a possibility. Call for appointment with an oral maxillofacial surgeon for his opinion.