due ot oxidative damage of skin some darkness dullness keeps occurring. You need to take care of your skin and reverse the damage to keep it healthy. For now, treatment will give response but you will have to continue caring of it. For darkness, loss of glow & dullness - there are antioxidant therapies like glutathione , lasers for rejuvenation, PRP therpy for facial rejuvenation , peels, etc. You can drop by my clinic or meet any other Dermatologist/Trichologist as per your convenience and get further evaluation done. Hope this was helpful