Is this the diagnosis from the neurologist you saw?

If you put in the search term "manx syndrome" on this forum, you will find plenty of information, and if you post a question someone with years of experience will respond within a day or two.

http://handicappedpet.net/helppets/

The only manx syndrome cats I've known at the shelter have needed to be expressed and have found a home with one of two vets who used to work there - luckily for them. It seems there is a wide range of disability within manx syndrome. Did the neurologist tell you how impaired Lynx is?

For diarrhoea try giving him Famatodine (Flagyl), which you will have to get from the vet, and put pumpkin (not the pie filling, just plain pumpkin) in his wet food. It works like a charm and it's worked perfectly with Zazesh. He's gone from streaming diarrhoea to normally formed stools which makes both our lives much easier. If you are diapering him while he has diarrhoea, you may want to put zinc oxide ointment on his nether regions under the diaper to stop any burning and rash. A&D is good also for burning.

Will you keep him as a foster? Has your rescue started trying to get him into a sanctuary?

Did the neurologist tell you you needed to express Lynx? My understanding is that if a cat leaks and does not create puddles of pee then some urine is collecting in their bladder and just sitting there. However, he's lived long enough without getting a UTI so perhaps he will be fine - except for leaking.

I only change Zazesh twice a day and he does well with that - no rash, no burning, no infection. I get the diapers from Walmart (making my first trip to one just for this purchase) and get 92 for about $25.

Good luck and keep us updated.