I am finding it difficult to swollow and it really is painful but I don't have a sore throat. What could it be?

Several posibilities. But without an exam and full history it is impossible to diagnose over internet. You should definitely see someone soon if this persists. There are many possible causes for partial obstruction of the upper esophagus. You don't say if you have been vomiting or have other symptoms. Go see a gastroenterologist.