I have melasma. I want to lighten these spots. My dermatologist gave me 4%hyroquinone gel as well as a tube of 0.025% tretinoin cream. Can I mix these 2 ingredients together and also add a moisturizer and apply to my face and body? At night? How long can this be done for? Should I be applying a moisturizer after I do this? I allready know about triluma but I allready have these ingredients and want to use them up first. Thank you.