My axolotl can't eat!

I am currently in full on panic mode. My lovely Axi, Spock, doesn't seem to be able to eat. He keeps opening his mouth to take in food and he just doesn't seem to be sucking it in, and if he does he either spits it straight back out, or he opens his mouth again to do that spit in spit out thing he does when he eats and it drops out.
It's really worrying, he's not eaten for a week, he's normally really greedy like he'd eat everyday if possible.
The other day when I tried to feed him he just seem disinterested and sat them opening and closing his mouth, then today when I've tried he's just done what I have previously explained.
He's currently sat in his feeding tank, with bloodworms, liver, and shrimp (something he normally goes crazy, he's just sat opening and closing his mouth.

I don't know what's wrong, I can't see anything in his mouth when he's opening and closing it.

Nothing has changed in his tank, water quality is at it's usual as well as it's temperature.
Please help I don't know what to do!

What are you water parameters? Temperature?
What do you have in your tank? What is the substrate? Is there anything your axie could of swallowed?

If you could answer these questions it may help people here figure out the possible problem.

Do you have any pictures of your axie? Is he acting/look any different then before that you can tell?

Water parameters are 45cm, 30cm, 20cm. I am currently waiting on the arrival of a slightly larger tank to move into as he is usually quite active.
Temperature is always between 15 and 20 degrees, I regularly check the water temperature every time I do a change. There is sunken driftwood that forms a low arch that he likes to sit beneath as well as a fair amount of low lying plants that he also sits under, there is a floor clearing which has a larger plant which covers a lot of the area above the clearing. There is also a low flowing filter which I have facing the wall of the tank so there is as little current as possible.

The bottom of the tank used to be bare but a few weeks ago I added sand to the bottom of the tank which so far hasn't seemed to cause any problems!

The tank set up, minus the new addition of the sand, has been the same since I first got him.
I always feed him in a separate bowl so I can monitor how much he is eating and make sure he doesn't accidentally eat anything he's not supposed to.

Water parameters are like ammonia nitrite nitrate and the ph.

I really dont know if everything is normal what it could be. Does he look like he is getting thin?

Ahh sorry my apologies!
pH is usually between around 7-7.5 whenever I test it, I also decholorinate the water whenever I do a change.
I am really concerned, he isn't skinny and hasn't visibly lost any weight it's just he appeared to lose his appetite and now when he is trying to eat he doesn't seem to have the usual vacuum effect that axi's have when he opens his house to eat.

When he opens his mouth can you see anything lodged in there? Does he look normal? As in not swollen.

Can you test the water for ammonia, nitrite and nitrate?

Nitrate levels. ammonia and nitrite and nitrate levels are all fine. I can't see anything lodged in his mouth, but his tongue is visible when he opens and closes it.

My little man was doing this for three feeds in a row and he doesn't eat a lot as it is... but on the fourth feed he had his three large worms (which is what they are both normally offered) and then pinched one my daughters were feeding to his tank mate.... since then he has spat out his last feed again...

His old owner assures me he used to eat every two days....

Hopefully he's just being testing like my little man was....

Hey guys!
Just to let you all know Spock started eating again a couple of days ago!
I still don't know what had caused him to stop for a week and a half, but he's been chowing down as normal once more.

I'm incredibly relieved as you all can imagine!

Thank you all for your support and advice!
Here's a little pic I took this morning when he was watching me eat my breakfast. (Like I said he's usually greedy! )