His 3 days constipation started on the 15th. Bought him for a deep water swim on the 18th and fed him there and the weird blinking and rubbing started after that. His eyes were slightly puffy when he'd close them after a few blinks. The next morning he pooped a little and stopped blinking so much. So I thought the blinking might have to do with UV over exposure. Also, during the 3 days he'd not go up on his 'basking area' and prefer to stay in the shallow water.
He stopped blinking on the 21st and pooped a bit so I thought things were back to normal until last night on the 22nd, I brought him for another deep water swim and his blinking recurred. He continued to behave weirdly in his shallow water tank, constantly digging around in the water as if he's still swimming and drinking a lot as he does that. It didn't stop for two hours or so, so I took him out and found him a bit puffier than usual. He also did the holding in breath + neck enlarging thing for ten seconds and did a weird yawn. This was when his eyes looked really puffy.
23rd in the morning he was still blinking a bit, he'd mostly close his eyes and rest and his eyes still look kinda puffy when closed. Then he pooped a lot (but ate it, all we saw was the water was dirtier than when he pooped only a bit) Brought him to the vet. The vet said he can't determine anything yet so he gave him a vitamin shot, and prescribed 5 more for self injection. When he came home there was sunlight for 10 minutes so I put him under there. He's still active when roaming outside and when begging for food, he has a good appetite like usual. But he got tired after his meal and mostly rested in the water with his eyes closed (It's a long day for him at the vets') By this time his eyes looked fairly normal even when closed. It's bedtime now.
Diet wise, on that day when the blinking started I fed him cucumbers, lettuce and bananas instead of his daily pellets and chyesim because I was trying to get him poop. Since then until today, I still fed him daily, reduced his pellets and chyesim and increased lettuce. And also bluberry (not daily)
Some background, he couldn't swim when he was a baby and still isn't a very good swimmer, so he'd always lived in shallow water. He also wheezes when he swims. I think he might be overweight, he eats his poop but we can't control that

