My firemouth has what looks like a large white pimple where his dorsal fin meets his body. The female started to get these around her gills, and also at the base of her body.
We had what looks like a very similar "pimple-like" sores on a couple of our rainbow fish... I was told it was a bacterial infection. We did lots of water changes to improve the quality of the water and they did go away... it took a little while and a lot of patience with pwc's. Good luck!