Something up with Squirt

[Alcemistnv]

So Squirt so far has been like Bubs, 100% healthy.

Squirt, for the last 2-3 weeks though, has been developing a weird behavior. He's become more aggressive (was flaring almost everytime I saw him), he gets bloated REALLY quick, his fins are defintiely not as they used to be, and he's been having peroiods of time where he literally will "play dead." He will either float at the top of the tank or on the bottom, and only reacts when I lift the tank lid. One time he actually twisted his way between the pot and the skull and stayed their motionless for a good few minutes.

I don't know what's going on, the tank is fine, especially considering Bubs has been showing no reactions like Squirt's at all. Plus, Squirt showed this behavior before Lucky came in, so I'm sure it's not Lucky. :/

He's also been looking a little loopy when he swims. Sometimes he'll lean on his side a bit as he's swimming around.
I know that about September 12th, he had scraped his head making a sort of bald spot, and in those pictures he was very clamped up (as I'm typing this Jingles tried to jump out of his tank -.-

Squirt playing dead


Bloated (this was after giving him his normal diet + a day of fasting)


This is Squirt when I first got him


He's been in the same tank for as long as I've had him with the same diet :/
Thanks to nyone who helps
(color in pictures are off because of lighting)

[Kytkattin]

What is the temp, how frequent are water changes, how big is the tank, etc. Can you block his view of the other fish temporarily? They might not have anything to do with his problems, but at the very least you can remove them as a stressor.

[Alcemistnv]

The only other fish in the tank he can see is Lucky, who is pays no attention to. Bubs is behind two sets of colored dividers.

The tank is at a steady 78, and the water changes are right now 2 times a week, 50%