My African Side neck is sick!

Question
Hello I bought an ASN from Petsmart about a month ago. I put him in a 45 gallon tank with a painted turtle. My asn was fine with the painted turtle. THe painted turtle was wild though and since I got the new tutle I decided to let her go after about a week of them being together. Well a week or two after I let the painted turtle go my ASN stopped eating. He looked fine I just figured he wasn't hungry. But then he start to get really sluggish. And I just noticed today that he is floating on his side, has a swolen eye (I believe) and every once and awhile opens his mouth while just laying there. Please help!

Answer
I have no hands-on experience with ASN's, but wild caught turtles are notorious for having parasites, and it is a common practice to not mix animals from different continents because animals have almost no resistance to foreign 'bugs'.

Floating on the side is often pneumonia, and one swollen eye is usually an injury or early sign of other problems.

I would strongly suggest a vet's visit. I am not sure there is much you can do at home for this guy.