I've had alot of blood i'm discharge and change in smell. today a sharp pain that comes and goes started in the lower left side of my back.

Infection? STD?: New or abnormal vaginal discharge or bleeding always needs professional evaluation, and you have both. With bleeding and odor, STDs are a good possibility; or perhaps bacterial vaginosis (although that doesn't usually cause bleeeding). See your GP or gynecologist ASAP, or your local NHS GUM clinic for expert, lifestyle-senstive care. Best wishes and good luck.