Upside down?

[Seascape2]

I have a 2 year old Axolotl named Starburst in a 40 gallon cycled tank, I do weekly water changes, the ammonia and nitrite levels are 0ppm and the nitrate is between 20/30ppm. Her tank is always kept around 65 degrees, and I feed her twice a week. About a month ago she started flipping on to her back and laying like that all the time. If I flip her right side up, she swims and then flips back upside down again. I'm not sure how to fix this or help her, she lays like this all day and hasn't been eating as much.

 

[wolfen]

might be better to tub in shallow water to prevent her from rolling over in the instance that there is some air trapped causing her to flip over.