Do my fish have white spot disease?

Hi,

I was just looking for some advice on some of my tropical fish. I've had a tank for about a year or so now, it currently has a mixture of guppies, angel fish, zebra danios, dwarf gouramis, various flat kind of algae eating loaches, clown loaches and some tetras: red phantom, yellow tip, white tip and neon.

Anyway about 5 days ago I found one of my clown loaches had died, after a look at the other one I noticed it was covered in white spots which after a bit of research I figured was white spot disease. I took a trip to the fish shop where they gave me some medicine (anti white spot) which I carefully followed the instructions for and have been using for about 4 days, meanwhile my other clown loach has died and for the past 2/3 days I've noticed all four of my red phantom tetra's have developed these white spots (two more so than the others). It's strange as it hasn't seemed to have affected any other of the fish and the tetra's are swimming round fine with it.

I have also been vacuuming the gravel regularly and after doing a fair bit of research online I have read carefully increasing the temperature of the water very slowly is quite an effective way to combat the disease. I've therefore, over the past few days, been increasing it slowly but not quite yet to what was recommended online as I know how sensitive fish are to sudden temperature changes.

I was basically just wondering if anyone had any experience of this and whether it definately sounds like white spot? I've read online sea salt can be quite good if used correctly instead of any medicine but obviously I haven't yet tried this as I'm not sure how tolerant my fish are to salt.

Oh and I haven't been able to segregate the tetra's I suspect to have white spot as my other tank (which all the fish are fine in) is full of barbs and I didn't want to introduce the disease to this tank obviously.

Thanks in advance for any advice