i have a 29 gallon tank
10 neons
7 fancy gupps
4 giant danio
2 zebra danio
2 sunset platy
1 dwarf gourami
Personally i would remove the Giant Danios, the tank isn't big enough and you have nothing that will challenge them for the dominant position amongst the tank. if they remain the dominant fish they will continue to act in this way and you will have more stress related illness occuring
You could also try and swap the Giants for more Zebras as they really need to be kept in a larger group,
Lastly if your in the UK, Protozin and WS3 are two of the best whitespot treatments in my opinion