I don't recognize those symptoms, if they were exuding black fluid, I'd say it looks similar to problems I've had with Hyalophora gloveri and euryalus.
Try Oxine, it's a food grade disinfectant that has saved larva for me in the past, you'll need to atomize it with a sprayer, the dilution is 500ppm
One gallon water with 100ml of Oxine, with 2 teaspoons of citric acid as a catalyst.
This recipe was given to me by another breeder who swore by this treatment and also claimed it could invigorate stock that was suffering sub-lethal infections.
I bought my supplies on Amazon, although you may find the chemical elsewhere, you'll need an industrial grade sprayer and brown storage bottles as well, the solution will eventually degrade a typical household sprayer.