Sweet little ones!
I would try sanitizing the water as explained in the article below. I would also apply Iodine or Povidone Iodine to the scabs that are appearing. Take care not to disturb the scabs, just put the Iodine on a qtip and dot it on. Worth a shot to see if it helps start drying those up or at least limit the eruptions.
Keep them drinking and eating the best you can.
Since you are having outbreaks like this, look into Fowl Pox vaccine, it may help future chicks, but I think it's administered around day 8, so you would want to do what you can to keep mosquitoes out of brooders until you can vaccinate.
https://the-chicken-chick.com/fowl-pox-prevention-treatmen/