Hello I am licensed medical esthetician. Please do not stop using just because your hyperpigmentation getting dark it is only gets dark because they lifted close to the surface of the skin. That means it works!
Do not worry about it! It did not get worst. Melasma is very deep hyperpigmentation problem so as they come close to the surface, they would look darker. That means it worked. As you do more, they ll get darker and darken and finally...