not himself

my axe called flubber is just not himself these last few days he is still eating but
just hides in his cave most of the time this is not like him at all he is normally so nosy
and watches us all day, he hasent any fungus or any injurys at all.
i just dont know whats wrong i am so worried this is the first one i have ever had so dont know
if this is how they act
please help

Ok I guess a run down on your set up is needed here.
Size of your tank?
Substrate used ? i.e. gravel
Temperature of water?
Have you tested the water for ammonia, Nitrite or nitrate?
Type of lighting if any you are using?
Food you have been feeding him?
How often do you carry out water changes and how much do you remove each time?
Do you use a filter and if so is it turned to maximum output?
Any other tank mates?
Location of the tank in your house...is it in a high traffic area?

Can't think of anything else right now, but if you can answer those questions it may lead to an answer.

Almost nothing to add right now to the encompassing questionnaire of Becky (well done, Becky!), just one addition:
How big is your Axolotl and do you know how old it is?

just like to say tanks for the replys. and flubber has started to come back out
to see us today, but to answer some of the questions,
he has large pebbles on the bottom of his tank much to big to get in his mouth
not sure of the temp, just room temp
havent tested water for anything
he has a normal 20wt bulb over his tank
he eats wax worms,earth worms,crickets,meal worms, and turtle food
water gets changed about half a tank every week full clean once a month
no tank mates
yes a filter but on low
yes in high traffic area
he is in a 3 ft tank, i have had him for about 5or6 months not sure how old he is
but when i first had him he was quite seethrough he isant now
thanks for the help and could you please let me know if i am doing anything wrong for him
as i would feel awfull if i am thanks
donnat

I'll try to respond to each point!
Pebbles need to be larger than an axolotl head.
The temperature of the water should be ideally below 20 degrees..if you have any heating on in the room or sunlight coming in it'll possibly make the water temp too high. Higher temps tend to make axolotl sick and prone to fungal infections.
Water should be tested weekly for ammonia, nitrate, nitrite . An ammonia build up will affect the axolotl badly. Most pet shops will happily test for you, but owning an axolotl a test kit will be very useful.
Axolotl tend not to like too much light, mine only have one on when I spot clean, feed and do their weekly water change..even a 20 watt bulb can heat water .
The diet seems generally fine...earthworms in my opinion are the best and I use these as the main food source .
Water should really be changed approx 20-30 % weekly unless you have an ammonia, nitite spike..if you do much more the tank will never cycle. This will help http://www.caudata.org/cc/articles/cyclingEDK.shtml
Monthly water changes/ cleaning should be avoided.
Ideally your axolotl should be away from high traffic areas as they tend to like being left alone..if you can't move it to another spot ( I appreciate it would be a real pain to move) then maybe covering 3 sides of the tank may help.
Lastly, I apologise if in the time it takes me to finish this post ( type with 2 fingers and in the dark!!) others have answered the questions!

The age of your axolotl will make a differance to how active and visible it is.
As they reach adulthood they become more [laid back ] lethargic and tend to spend more time in hiding.
This is mainly due to the fact they are no longer on constant food patrol as they are fully grown and dont need to eat so much.