cross reference the symptoms with the pictures and descriptions on @humblefish’s site. Recommended treatments should be listed for each of the main ailments
Looks like something my orange storm had. Started as a white patch on an orange spot and started turning reddish pink. Got it into QT and started treating with metro and furan. After a week it perked up and started eating like a pig. After 2 weeks I put it back into the DT. It's been fine since.
I would start treating right away. It progressed rapidly (overnight) and if I didn't start treatment immediately I think it wouldn't have made it.