Undergo virechana karma once in Ayurveda centre coz there seems to be pitta aggravation.
Later take medicines Saribadyasava 15ml with water twice daily after food.
Apply kunkumadi taila mixed with shatadhauta gruta.
A change in the texture of the skin indicates that underlying systemic (possibly hormonal) changes. You might need to get a free blood tests done. Are there any changes in your periods? Have your neck skin or underarms blackened? Have you gained weight? If the the answer to any one is yes then a thorough evaluation will be needed. So visit a dermatologist. You are young, so avoid delaying the visit to get th best results and to avoid permanent damage to the skin. Till your visit to the dermatologist, Make changes to your life style. Sleep early wake up early and most importantly EXERCISE ! Eat healthy and on time too . No junk food . This will help.