I really get annoyed when shops sell certain fish as "coldwater" species when in fact they are not. They can tolerate cooler temperatures than most tropicals (eg down to 18C) but not cold! :evil:
White clouds and the mussel are coldwater.
Danios need 18C or more and the other two are tropical.
22 Lires is a very small tank and you have too many fish for a tank that size.
Danios need a long tank as they are fast swimmers and reach high speeds. They are also a shoaling fish and are best kept in groups of 6 or more.
Assuming your flagfish are Jordanella floridae, they will get up to 6cm and need more room.
What sex are your swordtails? They need to be kept in a sex ratio of 1 male to 2 or 3 females. Of course, if you have two males you might be fine but the larger one will probably harass the smaller one to death as well as attack other fish. If you have females, have you considered what to do with the resulting fry? They can store sperm for many months so were most likely pregnant when you bought them.
White spot is an indicator of stress and/or poor water quality.
I would keep the white clouds and mussel and return the rest. Get more white clouds once the tank tests are clear. Watch the mussel. If it dies it will go off very fast and kill everything else in the tank. Since you already have white spot this is a distinct possiblity.
The fish are most likely sick (fin rot and/or ammonia burn) as well as damaged due to fin nipping.
The tank has been going 2 and a half weeks, why would you need to clean the filter? That is where the good bacteria grows. If you keep cleaning it you will kill off the good bacteria and the tank will never cycle. Have you read any articles about tank cycling yet?