Cat fell in love with the little dog

Please help me to understand that with the cat.
What's troubling at the moment is the cat constantly licks his lips and smacked his lips a little at the same time.
The background:
The problem was always how long I've lived.
Cat 4.5 years, neutered, British. Weight 4.3 kg. Eats Royal Canin for sterilised cats mainly dry, moist rarely as treats. The same vitamins with Catnip for brushing your teeth regularly. The stool is normal. Worms running every 3-6 months. Won't go outside, not counting the balcony (17th floor). The last 8 months sharing a territory with a 13-year-old Briton. Was inoculated against rabies because of the trip in the train 1.5 years ago.
I got on Craigslist 4 years ago. The previous owners gave 7-month-old kitten in good hands. Said that the cat gave them, he from a cattery, a purebred. Gave due to the fact that I had to move in with parents who have an adult dog. Dog kitten all the time drove, so it had to be locked up. A dowry was given a bag of kiteket and cheap wood filler (then it all went in the trash).
I started to feed the hills, but the cat is often sick. Several times a day, no food and no coat, and like just saliva. And changes in behavior had absolutely no. Ran, jumped, threw up, rode on. Cheerful, active.
I decided that the case in the stern and we switched to Royal Canin age. Vomiting became less, but completely the problem disappeared. Then I noticed that he often licked.
consulted with vet on the phone and advised me to give noshpu and yogurt. From noshpu we were drooling a river the yogurt he ate with pleasure, but immediately he himself was sick. The vet said that the cat had some stomach cramps. Well, to get rid of worms of course. It is also before castration was necessary. Then was sick less and less. Now it happens once a week approximately.
Cat hyperactive - when I am at home all the time bypasses the possession, playing, running, jumping, talking, picking on older cat.
I got used to the fact that he licks his lips and it began to seem cute habit.
Today I read that licking can be a sign of many different illnesses, even kidney failure... My cat very likes to drink - if included hears the water running at full speed and drink straight from the tap. I even hands can not wash. From the bowl, too, often drink. Writes several times a day. Suddenly all the buds???(((
Still a few disturbing things - he's very shy (any sharp sound, and we jump up or even hide) and he is not gaining weight absolutely. With 7 months to a year added grams 300-400, and then 3.5 years the same weight. He's not skinny, is a large slender cat. It was strange for me because the senior British quickly gained weight and now weighs 7.5 kg and in the best years, when we even on the diet was sitting, weighed 8.5 lbs. And the younger cat the older growth is larger and weighs much less.
I, of course, the alarmist and the Board next weekend in any case, you are lucky... But tell me, what will be?