I'm not a fan of pima or mela fix. It's not that some natural products can't work in very mild cases but if I'm going to dose I want real pharma drugs (my husband is a retired pharma chemist, lol).
Those may be a good choice for suspected columnaris. There are 2 forms: a red sores version that kills very fast & a more chronic slow form of white patches.
For internal parasites I like flubendazole (not the similar fenbendazole). I don't know if they can be used with kanaplex at the same time.
Both diseases seem to be hitting your corys quite hard, I'm sorry. Might be time for a second hospital tank in addition to your QT tank. Are any other fish showing signs of either disease? Both can spread...but some fish are more susceptible to either.
Those may be a good choice for suspected columnaris. There are 2 forms: a red sores version that kills very fast & a more chronic slow form of white patches.
For internal parasites I like flubendazole (not the similar fenbendazole). I don't know if they can be used with kanaplex at the same time.
Both diseases seem to be hitting your corys quite hard, I'm sorry. Might be time for a second hospital tank in addition to your QT tank. Are any other fish showing signs of either disease? Both can spread...but some fish are more susceptible to either.
). Whatever this is seems to only effect them which is the confusing part for me. 
