Clear Mass on Cat's Eyeball

My cat has a clear mass on his eyeball that appeared suddenly. My boyfriend says he has seen it once before but it was gone by the next day. He has also supposedly experienced some form of eye trauma in that eye sometime in the past (according to our vet). Finally, he is also recovering from an infectious corneal ulcer in his other eye at the moment.

If anyone has any idea what it may be, I would appreciate your input. Thank you.

Update: The clear mass has moved to the other side of his eye and is not as big anymore. It is almost gelatinous in appearance. 

Update: It is now gone from his right eye and is now present on his left eye (the one that is recovering from the infectious ulcerative keratitis).