Strange Growing Lump In The Middle Of Body

[Tubu]

Long story short, my discus is emaciating and she has a growing lump in the middle of her body.

My discus is emaciating although she does eat (not much recently though).
- About a month ago, I noticed she had sharp razor head and decided to transfer her to hospital tank so she could eat more and not being bullied in the community tank.
- She did eat more at first, but one day, I witnessed her puking 2 long chunks of digested food. Since then, she's nearly not eaten at all (for almost 2 weeks now).
- I noticed the round lump on her body was becoming more apparent (not sure if it's because she's thinner or the lump is bigger). I searched on the internet but there's no similar cases.

What did I treat her?
- For the emaciation: I assume she might has internal bacterial infection/parasite and did treat her medicated food (I mix API General with her granules) but she didn't touch any of it.
- For the lump: I did treat her with epsom salt but the lump didn't dissipate.

I intend to use a bird feeding syringe to feed her API General but I'm not sure of the dose. Could you guys give me some advices?

My questions:
1. Do you know what causes the lump in my discus?
2. Should I use API General or Metronidazole from other brand to treat internal bacterial infection? (syringe feed)
3. To deworm my discus, which should I use: API General or Flubendazole? (syringe feed)
4. Please let me know of the dose of the medicine that you recommend. (syringe feed)

More information: - I've had her for 1 year now, I always feed her Tetra Tropical Colour Granules (no bloodworm or beef heart at all)
- She used to have cloudy eyes for months and then her eyes just heal themselves (no swollen belly at that time)
- There's round worm in my hospital tank (I'm not sure if it came from her feces or from the tank. I clean the bottom of the tank daily and change water regularly but the worm never disappear).
I always vacuum wasted food in the bottom of the tank before I go to sleep, so please don't pay attention to the wasted food in the pictures.

I'm so desperate now, please help.