Black Ghost Knife fish with bump and white film

[29Gsaltaquatics]

Hello, I have a 3 inch black ghost knife fish. I have had him for over a month now, he has done great, but today I saw he has a bump on his jaw. It seems internal, it is about 3 mm in size. I took him into a QT for a second and he came to the surface and I put my had in, and he started rubbing himself on my hand and some tiny pebbles came out of his mouth. Second he just got this white film on him. It is only on parts if his sides and gill cover. He has a white string coming from under his head, but I heard that is where their anus is so I think that is poop. He swims, eats, and acts normal. I know 29 Gallons is small for a BGK, but I will move him someday. Please don't tell me to get a bigger tank for him because I will, it would just be a waste of time. Thanks for your help

Tank Mates:
1 Angelfish
1 Dwarf Gourami
1 Dojo Loach
1 Twig Catfish
6 Serpae Tetra
1 Mystery snail
3 live plants

Tank Parameters:
Ammonia: .05
Nitrite: 0
Nitrate: 1
pH: 7.0
phosphates: 0
dKH: 3

Aquarium information:
29 Gallon (I will upgrade someday for BGK)
Live plants
Black big grained sand
Lights on for 8hrs
Food: Bloodworms, Flakes, Krill, small and big pellets, and sinking pellets

Experience:
Saltwater
Reef Tanks
Brackish
Freshwater Community
Freshwater Live Plants
Livebearers
Goldfish and Koi

 

[29Gsaltaquatics]

I think white film is from me touching him

 

[Brookster123]

How old is tank?

 

[29Gsaltaquatics]

How old is tank?

A month

 

[29Gsaltaquatics]

He is doing better