Axy swollen and cannot close mouth

[gougeaway]

Hi all! My little buddy Mugatu (age 11) is not looking so hot.
His head looks very swollen and he does not appear to be able to close his mouth. His gills are also looking even more sad than usual (they've been very sparse for about a year or 2 now)
We relocated his tank a few days ago and did a 50% water change.
Any ideas what could be going on or how I can help him?

 

[debadog]

Hi all! My little buddy Mugatu (age 11) is not looking so hot.
His head looks very swollen and he does not appear to be able to close his mouth. His gills are also looking even more sad than usual (they've been very sparse for about a year or 2 now)
We relocated his tank a few days ago and did a 50% water change.
Any ideas what could be going on or how I can help him?

A picture would be helpful for diagnosing the problem.