My last Cocker, Joshua, became ill very suddenly one day when he was 15 years old. I'd been out with friends for Sunday lunch and when I got back Josh, having seemed normal in the morning, had diarrhoea, had been sick a couple of times and was very, very sleepy and lethargic.
The vet immediately said that it was a liver problem and blood tests confirmed that. I can't remember exactly what medication Josh was put on as this happened 7 years ago, but it definitely included antibiotics. I think the problem was an infection but we never knew what caused it.
We had a few days of him being very weak, but he was eating small meals and kept hydrated. Most of the time he just slept and he wasn't in any obvious pain. I think the vomiting was the difficult thing to get under control. Like Max, he found it difficult to get to his feet when he'd been sleeping, so I used to help him up.
The vet couldn't really give me a prognosis but warned me that Josh mught not recover. I decided to give him some time because, as I said, he didn't seem to be in any obvious pain (and he was a real wimp about pain, so I think I would have known). I know the vomiting must have been unpleasant for him, but as he seemed to be peaceful when he was sleeping and was able to eat small meals I wasn't willing to let him go without a fight.
Josh made a full recovery and went on to live another year and a half in good health for an old boy and had no further liver problems. I don't know if Max has the same as Josh but if so, I hope he will recover fully and get his quality of life back. I had some sort of instinctive belief that Josh was strong enough to fight the illness and had a good chance.
Josh was my first dog, so my first experience of care of a geriatric Cocker. I used to worry that I wouldn't know when to let him go, but I'm sure that I made the right decisions for him. It was a mix of taking a step back mentally to look at his quality of life but also relying in my instincts.
I really hope Max gets well soon and you have your happy boy back to normal.