I am on day 7 of this antibiotic and medicated food without the slightest sign of the cories getting better. I am trying one more parasitic medication next week after a few days break. After one more month if I haven't gotten a handle on this, I am going to rip my tanks apart, sterilize them and start from scratch.
I hope it doesn't come to this. I am going to try a mild bleach solution to sterilize my plants, I assume this will kill anything probably including half of the plants. I'll have to find a way to sterilize the substrate so I don;t have to buy new, the black sand was expensive. My lfs will get a huge load of sick fish, only fair since they sold me the sick apistos and left me out to dry after telling them about the first death.
Now I am breathing easier, instead of thinking of quitting, I have a proactive plan in case this doesn't work out.