You may have answered some of these questions before… it I don’t want to look for answers in this long thread…sorry.
What supplements are you using now and how often for each? How heavily do you dust the insects? What are you gutloading/feeding the insects now? I’m particularly looking for calcium, phos, D3 and the forum of vitamin A.
You said he can’t swallow…can you get a photo of inside his mouth wide open? Have you tried giving him small bugs like half grown crickets (size and softness of them might help. I would put one between his teeth when his mouth is open as he’s drinking. Does he drink?
How old is your UVB bulb? Is it a long linear one?
I’m not happy with the look of his eyes. He really needs a good chameleon vet to look at them…but I know that you can’t see one….so I don’t know what to tell you to do about it.
The following comments are only possibilities…you need a vet

to help figure it all out.
The tongue could be giving him problems due to an injury (but it’s been a while so I don’t think it’s likely), or due to a supplement/nutritional imbalance….which could also be a part of the eye issue. If the tongue muscles are weak due to a calcium imbalance, the tongue could misfire…shoot out with little control. That could be part of the difficulty swallowing too.
You could try using “bug juice“ for a short while…
https://www.adcham.com/html/husbandry/bug-juice.html
Wish I could give you a good answer…but I’m not a vet.