Hi

How to get rid of dark spots on your neck ?
You should do clinical assessment in the nearest medical center as for fungal infection you can Use creams such as Triderm twice daily and wear comfortable and clothes that are made of cotton and tp Pay attention to your personal hygiene . Your doctor will prescribe Hydroquinone creams and lotions or Retinoid solution like retin-A . In some cases : Laser treatment or Chemical peels
What are the causes of dark spots ?

• Fungal infection
• Extreme sun exposure
• Skin diseases
• Genetic factors
• Ultraviolet rays
• Hormonal disturbance
• Other causes 

What to do at the moment ?
You should follow the tips and advice provided to treat the dark spots . If there is no improvement , you should consult your dermatologist for assessment