accutane working?

I am now taking accutane for the second time in two years. The first time I was on accutane I took the lowest dose and my acne was mild to moderate. However, I stopped taking the accutane at four months due to financial limitations. My skin was clear for about two to three months afterward and progressively went back to normal. Now, I am taking 20 mg of isotroin which is the highest and am taking one once a day. I have been on this prescription for almost two months and have four more to go. My acne has gotten better except for these whiteheads under the surface on my chin and jawline. These never go away unless I pop them (it rarely leaves a red mark so I know they are right at the surface) and then they come right back two days later! Should I up my dosage of the isotroin and hope that it pushes the whiteheads out or should I stay on the 20 mg for a little longer?