@GreenCanuck you need to use some hydrogen peroxide in your next Watering as I think you may have some root damage happening there 5mls to 4 litres flushed thru your soil should kill that bacteria and save your Plant from
eventual death.
Use Voodoo Juice, SM-90 or Hydroguard, I believe you have root rot. The 5 gallon you are using is not great for drainage and not ideal to let oxygen to your roots. I imagine you've made drainage holes at the bottom.