Black spots like lentils on Ambystoma, please help!!!

[Alvistomax]

Hi, i´m from spain and i´m new in this. I log in in that forum because my Ambystoma mavortium mavortium have a big problem. Two weeks ago he left the food and he start to become more shy. One week ago some black spots appeared on all his body surface. I know that it is a fungus or something like that. I prove all things, salt baths, silvadene, dry land, change of all its "house"... but nothing work. What can i do????? i don´t wan´t my ambystoma death...
I can´t fix a foto but they are like little perfect-round black lentils in all his body.