This sounds reading through your post that your tank was not cycled. Assuming this I will say what you mast likely have is Ich induced by stress from high ammonia and/or Nitrites. Other common causes other then water quality are new fish bringing it from the store, drastic temp changes, fish that are incompatible stressing each other out and a few more reasons.
I would like to know if by chance did you change or clean the filter cartridge (I'm assuming you have a HOB ?) just recently? The directions often tell you to do this but to keep a healthy cycled tank thats incorrect. If you're not aware of how to cycle thats another issue we can help you with(and it is very important).
Now with all the stuff you've put in your water I'd recommend a huge water change.. 80% would be great. Make sure the water is similar temperature going back in. Also grab a bottle of seachem Prime water conditioner and dose two or 3 times the regular dose(I'm suggesting this to help with the most likely high Ammonia & maybe nitrites .. it'll temporarily neutralize them *thats the simplified explanation lol..don't want to get to crazy with details
). After this crank the heat up to 86f.. this is all you need to do to treat ich. Leave it at that for 2 weeks. I can't say if it's too far gone.. but hopefully they'll get through it. Salt isn't needed and snails can't tolerate it. Medications really rarely are useful or needed and often can stress an already stressed fish more..not to mention you! PH adjusting products are 99.99% bull ..give or take .1%
. Well the do screw with your PH, but they make it unpredictable and unsafe for the fish.
1 last thing..are you testing your water? if so with what? and what are your readings?