I need some help please! why have my gums suddenly started to bleed?

Poor oral hygiene: Plaque and calculous deposition in the area of poor oral hygiene will cause gingival inflammation and ultimately gum bleeding. Malocclusion will also induce trauma to the ligament, open the contact, encourage the food impaction, and ultimately leads to gum bleeding. Finally, an abscess (tooth abscess or periodotnal abscess) will try to drain and may cause bleeding. Check with your doctor.