Help! Axolotl not eating, doing a "throwing up" motion

[Tjebb]

So I have had Dollar for about a year and a half now. He is usually in good condition, other than a few ammonia jumps that happened in the earlier years. He hasn't eaten in a about two days, and he keeps trying to "throw up." I keep moss balls in the tank, and I am worried he decided to eat one. Does anyone have any advice? The poor guy's tail is curled at the tip, and I don't want my baby stressed!
His tank was stable when I last checked, but I will check it again and post the results as soon as I can.

 

[Tinamlat]

The moss balls were small enough that he could swallow them? Is he showing any other signs of possible impaction/ constipation?

 

[Tjebb]

He ended up getting it out of his mouth. I don’t even know how he got it, cause the only moss balls I put in there were large. He probably tore it off. Thank you for your help!