Need help with Fish

[The Orchid Boy]

Hello everyone! I know most people here on Orchid Board are orchid people of course but I need some help with my 10 gallon aquarium.

For about 3 months my aquarium would get cloudy overnight and I would progressively change the water till it was clear. Then just about a week ago it stopped getting cloudy. I had 1 male betta & 3 female bettas. One of them started swimming funny and sideways for a day and then died. Then I noticed a small white bump on one of my female betta's 'nose.' I assumed it was a fungal infection and I treeated her twice and it isn't going away. What could have caused the cloudy water? What do I do to make the fungal infection go away?

I have tried other fish and they all die in just a week or two. I researched forever on each fish that I tried. I set the tank up, cycled it, tested it it and everything seemed and still seems perfect. I am just about ready to give up.
I need some help.

Don't tell me anything about how male and female bettas can't be together. They have been living peacefully together for over a year. There are two many myths about bettas! They are also abused way too much.

---------- Post added at 10:54 PM ---------- Previous post was at 10:50 PM ----------

I tested the water myself and had it tested by a fish store. The levels of everything and the temperatures, pH ect. are all perfect. I used a mixture of hard and soft well water and the fish store said that that's fine to use. I have been using it fr a year and the bettas were fine till now.