I am starting to doubt myself that it is an amano shrimp. Someone mentioned elsewhere that it might be a Malawa Shrimp? We have ghost shrimp in the US but I think they are different from the google search from Australian river shrimp.
I ordered some oil of oregano that you listed off ebay and hope it will help. Unfortunately it will take a few good days to get here. In the meantime, I've been putting a little hydrogen peroxide in the water. So far it's still staying pretty hardy and eating. I put extra floating plants in the tub from the start of quarantine and today I dropped a small piece of algae tab in there. The shrimp still prefers to feed off the floaters. When I dose the food, should I remove the floaters so it concentrates on the medicated food? I have the floaters in there for comfort along with natural food and filtration.