Poor Monty and poor you.
I know exactly how you are feeling, I went through a similar thing earlier this year. Its such an agonising wait, and its very difficult not to think the worst.
At the beginning of this year, I was sat stroking Sapphi when I suddenly felt a lump on her back. The next morning I called the vets and took her in that day. It was quite a large lump, but there wasn't any obvious entry point for a foreign body to be in it. They took an aspiration of it and sent it off to the lab. We had to wait a week for the results to come back. The possibilities that were discussed were a tumor, infection, allergic recation and foreign body.
When the vet rang me I could tell in her voice something was not right. They'd not been able to get a diagnosis from the aspiration, which isn't altogether uncommon. The lab had offered to run the test again on another sample free of charge. I discussed the options with the vet and in the end we both thought removal was the best way forward. So the next day she went in and had it removed.
The lab carried out a hystology on it which was inconclusive. They think that she could possibly have had a knock, that her body has reacted to.
Sapphi, in herself, had been much quieter than normal for about six weeks. She'd just turned two and we wondered if she'd just grown up a bit and settled down. On the day of the op, I expected her to come home feeling a bit sorry for herself. My OH picked her up on the way home from work, and she came running in the house, all excited like she'd just come back from a walk in the park. I was amazed, but what was the most amazing was that she'd returned to her normal bubbly self that very same day and has remained that way. The vet said that it must have been giving her alot of pain, to have made her so quiet for so long to return to normal the same day it was removed.
I hope that you get the good news that we did. I just wanted you to know that its not always bad news and there is still hope.
I'll be thinking of you and Monty on Friday. Sending you positive thoughts and cocker kisses from Barney.