Thanks for the additional information although I'm sorry that I was off my computer when you responded back.
I not entirely certain that this behavior is secondary to internal parasites although I can understand why you might think it would be.
This sounds like he may have a milder form of a condition called Hyperesthesia Syndrome (LINK
). There's a range of "odd" behavior with cats who have this syndrome which range from occasional excessive intense licking to almost seizure-like activity.
There are no specific tests which can be done to diagnose this problem but rather we suspect it based on an individual cat's behavior as described in more detail in the article I provided above.
If my patient only excessively licks near the spine in front of the tail base, then I'll want to rule out fleas but in most cases, these cats are creating sores or scabs on their bodies. But, if there's any doubt about whether fleas may be playing a role or not, use of a good topical product such as Advantage or Cheristin should be considered. Since he does go outside, unless it's the middle of winter with snow on the ground where you lie, then fleas may play a role in his behavior (even if you don't see evidence of them).
For the milder forms of Feline Hyperesthesia Syndrome, I don't typically suggest any medical treatment options. Once the owners recognize the underlying problem, they usually agree that medication isn't something they want to give their cats.
Since there may be an OCD (obsessive/compulsive) component to this behavior for some cats, environmental enrichment (such as interactive toys, etc) may be of benefit. This suggestion may not necessarily apply to him, though, since he does go outside and I'm certain that he finds lots to do when he's out there.
And, as to why he seemed improved after he ate, I can't necessarily make a connection with the behavior stopping unless he was just distracted by his food.
It's not been my experience that this behavior worsens as these cats age although I suppose it's always possible that it could.
I hope this helps although, again, my apologies for the delayed reply. Deb