The basic rounds of questions we ask are:
What is the water quality? Ammonia levels, nitrite, nitrate and pH. A freshwater aquarium testing kit can be purchased to get these numbers if you don't have one. Local fish and pet stores will often run the tests too. Liquid tests and more accurate than strip tests.
What is the water temperature? Axolotls are a cold water species and need temperatures around 16C and 18C.
Was the tank cycled before you added the axolotl?
What is the diet? What are you feeding and how often?
Does the tank have a filter? What kind and is it buffered if it's creating a lot of current.
Axolotls are fairly sensitive to water quality issues, and most problems can be fixed by correcting water quality. It helps to know if your area has a lot of heavy metals in the tap water too, if you use tap water during your changes. There are water conditioners that have added elements to remove heavy metals if you suspect that to the problem. Most commonly on the forum the water quality issues encountered are high ammonia from an uncycled tank, or high temperature stress.
It's also nice to have a picture of the axolotl, to see body quality and such.
