Only one of the fish in the pictures has white spot. There are a couple of fish with excess mucous on the edge of their tails.
Do a big water change (80-90%) and gravel clean the substrate. This removes a lot of the parasites. Clean the filter too if it hasn't been done in the last 2 weeks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
How long did you have the temperature at 30C last time?
You need to keep the temp up for 2 weeks or at least 1 week after all the spots have gone. You can raise it to 31 or 32C, if 30C isn't working. Or use a medication containing copper or malachite green.
The shaking could be them displaying or arguing over territory.
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If you have to treat the tank do the following:
Work out the volume of water in the tank.
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.
If you have big rocks or driftwood in the tank, remove these before measuring the height of the water level so you get a more accurate water volume.
You can use a permanent marker to draw a line on the tank at the water level and put down how many litres are in the tank at that level.
There is a calculator/ converter in the "FishForum.net Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.
Remove carbon from the filter before treating with chemicals or it will adsorb the medication and stop it working. You do not need to remove the carbon if you use salt.
Increase aeration/ surface turbulence when using heat, salt or medications because they all reduce oxygen levels in the water.
