Sorry to hear about your losses - Yes I did lose several fish - all 13 Cardinals which were the first to succombe, 2 Guppys, 1 Platty, 3 Clown loach, 4 Ruby Nose tetra's, and worst of all I accuired a beautiful fully grown Albino Angel after I though the ICH had cleared up - sadly it too became a victim (badly in fact). Half of my stock didnt actually get the spot, most of those that did actually survived - the spots became apparent on other fish over a period of several days but by that time I had already started using the Meds so the spots never really got a hold. To start off with however it was really bad and I was gutted to loose so many fish.
Keep the meds going is the only advice I can give but to pass on the advice from the LFS, dont mix the meds, start with one and continue to the bitter end - therefore check that you can actually use your medication over a prolonged period. I changed my water as often as possible also - roughly 20% every 3 days or so and making sure I gave the sand a very good hoovering to try and capture the white spot cysts that had dropped off awaiting the next stage of hatchment.
Hope this helps.