Another Fudge trauma.... update with a bizarre ending.

Over recent weeks he has been developing a hard lump on his back under his fur which has recently become nearly the size of half a tennis ball.
He was not discomforted by it, seemed in no pain and didn't mind it when it was rubbed or touched.
The vet has seen him twice and admitted she didn't know what it was. It wasn't a tumour like growth, just a very large swelling. She'd tried to see if it would drain but actually very little came out of it.
Today it was still as big as normal..... until I came in the house at lunchtime. It had completely disappeared.
We've been back to the vet who is now totally perplexed. She has taken blood samples to see if anything else is going on inside so I await those results this afternoon.
He has become quite weak and wobbly which is not like him, apart from his age, so I'm wondering what the heck is the matter. Has this thing burst and done something internally?
Poor old lad, he doesn't deserve this.

 

Just seen your other thread, the 2 must be linked.