Why do i have whitish yellowish patches in my mouth and my mouth is dry and gums bleed when i brush my teeth ( i brush and floss every day? and have sinus pain are these related or no?

Multiple problems: Sounds like you have multiple problems, with multiple causes. Just brushing and flossing once a day won't cut it. Please see a Dentist to be examined, properly diagnosed, and properly treatment planned. Your Dentist can help you get healthy and stay that way.

Must see Dentist : The white patch may be Lychenplanus but must be evaluated by Dentist . Just brushing and flossing is not enough , every one needs to have Dental visit at least twice in a year for check up and professional clinic . At times the white patches comes and disappears itself without any treatment. Many patients have the white patches increase with stress and lack of sleep , alcohol based mouth washes