Question: Hmmm, what do you think?

So, my axie's not been acting himself the past two days. Usually he is movin around the tank floating about, waiting for a juicy worm but the past two days he's been on the ground and just really sluggish. I didn't really think anything about it at first but tonight he was doing something really weird.

I was doing a water change of about 20% and when I was done I looked in to see what he was doing and he was like coughing, looking like he was going to cough something up but nothing came out. Like repetitively though for about 5 seconds then stops then 5 seconds later he was doing it again off and on for like a minute. I thought he might have swallowed something (which there's nothing in the tank that he could have swallowed unless a big piece of a plant)

water temp: 70
Not very much current
substrate: sand
20 gallon tall with just one juvenile (4.5 inches long)

Anyway just wondering if this is something others have seen there's doing or if it's something to be worried about? I checked my ammonia and it showed up next to nothing.
I did find a regurgitated worm when I was cleaning the tank today, I didn't notice it at first cause he hid it under a plant lol. Dunno, I stuck him in the fridge just in case he is trying to pass something and he can't or needs to throw up something.

Basically just looked like he was coughing and then his mouth would stay kinda open in between "coughs".

let me know what you guys think. probably just overreacting.

Doesnt sound anything to worry about to me, I wouldnt worry mine seem to spend an awful lot of time YAWNING or thats what it looks like lol, but they have done it for years with no ill effect.