as our lives progress, we come into contact with negative energies that taint our chakras and cause impurities such as dark energy. if you spend some time doing chakra meditation, they should go back to normal.
Chakra cleansing and meditation should fix this. Being focal points for your energy, they often get "muddied up" by your energy and that which you pick up from around you. If you have access to crystals, celestite works wonders for cleansing and balancing all the chakras. You simply meditate with it on your crown. You can aide it by doing a cleansing with visualization.