Funny tail?

[tlow]

One of my 3 juvie axolotls arrived to me in pretty poor shape (curled gills, missing toes) and now I've noticed that her tail is looking weird as well. My two main concerns are:
1) if it is something I should be concerned about
2) if so, how I should treat it, and if it is communicable to my other 2 axies
My water is at a pretty constant 19-20 degrees Celsius. However, my water parameters haven't been great the last few weeks. First my ammonia was really high, now the nitrate and nitrate, which leads me to believe my bio filter has crashed. I have been remedying this by doing 30% water changes every day/every other day. Today's parameters before water change are as follows:
Ammonia: 0.25
Nitrite: 2.0
Nitrate: 40
I feed them earthworms when I can find them, if not then they get bloodworms.
Any help would be greatly appreciated.

 

[tlow]

To clarify, as shown in the picture above her tail has gone white at the tip, and for lack of a better way to describe it, has gone all wavy along the length of it; almost as if the tissue has been eaten away. As far as I know she has not injured it in any way, all three of the axies in that tank seem to get along very well - nobody has ever been injured or lost any limbs while living with me.

 

[Skudo09]

The tail doesn't look that bad to me. I would be more concerned about the nitrite level. 2.0ppm for nitrite is way too high... I know this is before a water change but it needs to be kept much lower than this. Can you place the axolotls in a tub of cool dechlorinated water and re-cycle the tank without them in it? You can change 100% of the water in the tub daily and put the dirty water in the tank to help the cycle. This would be a safer option if you are not able to keep ammonia and nitrite at a safe level.

Cool clean dechlorinated water will help him out.