big lips on my red eye tetra

[elmo]

please can you help, I noticed last night that my red eye tetra has very big lips which look red and inflamed, he can't shut his mouth. i have been doing some research and have read that it could be dislocated or have a bit of gravel stuck. however when i feed yesterday he eat, he seems fine in himself.
All stats are fine, the tank is overstocked but i do water changes every week cleaning the sand and the glass there is nothing he could have got stuck.
I am worried about him, any advise of what it could be i would be grateful

 

[Sky042]

If you can get pictures that'd make things a little easier.

 

[Def]

We call this the Leslie Ash disease...

 

[elmo]

how do i enter a pic and what it is Leslie Ash disease?