Hi Tanja, I'm sorry you seem to have had a setback here. Don't beat yourself up over this... it happens. I may miss something if I read back through so let's kinda start fresh from the last 2 days... I want to separate the white feces issue from the external issue and treat them separately. The white feces is probably a side effect from the original illness and is not an immediate concern.
Do they seem to be coming out of the external issue? In many cases the salt alone will take care of this, but Furan 2 may be needed if there's no improvement. I just don't like using meds if they aren't necessary.
Your water - I wouldn't be concerned with slight ammonia readings if you are using Prime. Like Pat said, Prime can give false positive readings for ammonia. The element is still there but has been neutralized for good but you can add a little extra if you think it's needed.
Are you aging your water? Are you changing water daily?
The bottled bacteria - How much have you added? I've never use this stuff so I'm not sure if it can create an issue if too much is added. When I've had an uncycled tank, I just keep up with water changes and the filters always seed themselves.
The jumper - this can be very bad, but if it's still alive it may bounce back and it's a good sign if it's still alive after this much time. I would keep lights off when you are not doing maintenance.
Can you give us a photo of the whole tank?