Carboxytherapy for one arm that's harder than the other after lipo?

I had the one month appointment with my doctor today for lipo. One arm is harder than the other and more painful, but my entire body is still sore. The doctor said to get carboxy therapy for my arm. I don't want to keep spending another 600$. Do I really need this? Or will my arm heal and go back to normal on it's own? It doesn't look weird or indented, it's just harder than the other.