Flicking gills, lethargic

So my axolotl just started acting kind of weird the last 24 hours. Yesterday I did a normal weekly water change and gave him his Sunday worm, then before bed he was kind of hiding in a corner and flicking his gills a lot. Normally as I get ready for bed he's right at the front of his tank, watching me and swimming back and forth, so I thought it was weird he was being so antisocial. This morning he was hiding in his cave, still flicking his gills. When I got home from work, he seems to have thrown up sometime during the day cuz there were worm bits and mess all over the front of the tank. He's back in his corner, flicking his gills more.

He just looks uncomfortable, and with all the gill flicking, I'm worried that something is stuck in his throat. Obviously he already threw up once, but he still looks icky. I have no substrate in my tank at the moment, and I don't see any bits missing from my fake plants that might have been bitten or anything. Any ideas? He's my first axolotl and was raised painstakingly from an egg, so I'm a very worried mommy since this is the first real problem I've had with him...

How often is he flicking? It's pretty normal for them to do it a lot.
Check your water parameters, temperature etc just to cancel out the possibility of water quality problems.

I've had him for almost a year and a half, and this amount of flicking is unusual for him. It's quite frequent.

My temperature stays around about 19C and I haven't noticed any recent fluctuations. My pH is somewhere between 7.3 and 7.5. My ammonia is between 0-0.25ppm, although I did just clean up his big throw-up mess and have been siphoning the little bits that keep emerging. My nitrite is 0ppm, and nitrate is 20-30 ppm.

He's still really lethargic, and when I put my fingers in the tank and wiggled them, he barely glanced up, then ignored them, even when right near his head. This is REALLY unusual. His back legs look a little more splayed than usual, but I'm not 100% sure. :/ I don't know what else to do. I'm worried to offer him another worm if he's backed up or will just throw it up again...

If you are worried about him vomiting, then maybe fridging him would be a good idea. If he's stressed for some reason this will de-stress him and if he is backed up, this will clear it.

Phew, good news! I was so stressed all day at work worrying I'd come home to a dead axolotl, but instead came home to a big pile of poo in my tank. Looks like his new worms didn't really agree with him and he was blocked up at both ends. After a puke and a poo, he's acting a little more normal. His usual personality is coming back, and he's a lot more aware of what's going on in the room. Yay!! Now to switch back to our usual worms... >_>

Glad to hear it

Thank you for your support!