OK, thanks. With pale gums, and being very lifeless and quiet, I am worried about a few possible issues, including heart disease (which can appear suddenly in cats), anemia (low red blood cell count, which occurs slowly but the symptoms can appear suddenly), or internal metabolic issues such as kidney
or liver disease, both of which also tend to occur fairly slowly in older cats but can appear suddenly due to cats' ability to hide minor illness fairly well.
Obviously, without some diagnostic tests, it is extremely tough to know what's going on internally, but some simple supportive care measures may be of benefit. Some chicken broth, or tuna juice, can be trickle fed into his mouth, to help provide some hydration and electrolytes. Keeping him in a warm place, as comfortable as possible, is also a good idea.
Over the counter medicines are generally best avoided in cats. However, with the weepy eyes, there's a possibility there could be an upper respiratory infection
, which might be helped slightly with an antihistamine such as Benadryl (diphenhydramine), 1 mg per pound of body weight, every 12 hours.
Veterinary care is likely to be necessary as soon as it is available.