I have a couple thoughts here. One is that depending on what you're taking as an antifungal, the candida develops a resistance to some of them after a while and you have to rotate antifungals every couple weeks to keep them effective.
Another is that the body may get a bit overwhelmed with the reactions and the die-off can stop for a while, then after the body builds up more strength, you get another wave of die-off.
That seems to be what I'm going through. I've been taking Candex for a couple months. There's not supposed to be any die-off reactions from it, as it just dissolves the candida rather than "killing" it. But I've also been using pau d'arco tea and caprylic acid. I seem to get some die-off symptoms every other week or so.