Hi A.,
Fever blisters will not appear (or can be caught) if the immune system is working right. Melaleuca oil will heal them and ice will slow the metabolism of the virus down so no more will appear but the main thing you need to do is improve your daughter's immune systems. All of us that have had chicken pox or shingles or has a mother that passed the virus to us in utero have a dormant virus that will rare it's ugly head when our immune system is weak.
There are simple ways to pump up the immune system and if you're interested, I can give you a run down of what we have done in our home. We hardly ever get sick and if we do, it's quite short lived and normally no one else catches it. Antibiotics and the other meds you have given her are simply weakening the immune system more. They may target a certain issue but their bodies will be more susceptible to catch them again.
Hope this helps...
M.