Illness/Sickness: Axolotl face up

[albinoaxolotl]

The last week I ve found my axolotl face up a few times, he also have a big black spot with little red spots in his belly, he has not eaten in more than one week. Please help!

 

[Eternie]

Get your water tested, his tail is curved as well, so possibly stress? But Ive never seen or heard of one floating face up, hopefully someone who knows will weigh in soon.