Sorry to hear you are having problems with your Apisto.
It is really hard to say what the problem is, but it is easy to kill sick fish by treating them with the wrong meds. I am not that familair with melafix and pimafix, and whether or not it would raise your pH any, but I am very familair with clout, and it is a very nasty med. It sounds like you treated the entire tank including the fry and male? and I am hoping you don't lose any more. Treating a community tank with one sick fish is endangering the rest of the occupants, and when using something as strong as clout, you don't want to treat an established tank, in addition to staining your silicone, it is likely to stress the healthy fish.
It is unlikely that you will figure out exactly what happened, you may be able to come up with a theory. Although your fish appeared healthy and even spawned over time fish kept in the wrong conditions can come down with unknown problems, and this could be the case. If fry were present and the male was encouraging the female to spawn again, she could have stressed out. It is just hard to say.
In the future it would be best to have a hospital tank available for treating sick fish. Try to get your pH down, either with additives that lower it, or with R.O. water, it will help them live longer. And last but not least, it is best not to treat fish unless you are positive what the problem is. Clout is actually a pesticide, and while it does work well on parasites, it isn't recommended for anything else. It is commonly used for Malawi bloat, and while any cichlid can get bloat, it is not as common in South American Fish. Bloat is a wide used term, and can mean anyting from parasites to a bacterial infection, to an actually bloated fish. Your fish appeared to be sick, before the white spots appeared, which leads me to believe it was stress for some reason, and because it was stressed the immune system shut down, and parasites were enabled.
Step back take a look at your tank, and decide if you need to make any changes. We already know you pH is too high, if you are not changing enough water, or not changing your water enough, this could also contribute to the stress. Ten percent water changes only dilute the problem.