This description sounds like acanthosis nigricans. This is a condition where your skin​ folds like underarms, inner thighs or groin, neck and face becomes dark. It is either genetic or due to sedantry lifestyle and overweight. This can be treated. Please call me or contact me with photos using online consult option for proper diagnosis, treatment advice and prescription. ,,,

U r suffering from seborrheic dermatitis.. Medicine available for good improvement...... Do direct online consultation  by sending photos, otherwise meet me at my clinic, for accurate diagnosis and treatment