Hi I Have Been Taking A Medication Named PIGMENTO Since

Hi I have been taking a medication named PIGMENTO since 6 months under a demetologist's prescription for a small white patch that appeared on my lower back. I have noticed that my entire body has turned 2-3 shades darker. I am a fair complexioned woman 46 years old with glowing milky skin. Is this a reaction to the medication? The white patch is still there, hasn't blended in with my skin tone.
Please advise if this is normal and if my skin will come back to its original complexion?

Thanks