Hi. blood is actually quite common during a cold. the nasal passage is irritated. My sons and myself often have bloody mucous/nasal discharge when sick with a cold. The green/yellow mucous is indicative of pus being present. That makes the possibility of an infection real such as a sinus infection. Sinus infections are not contagious as they are the secondary infection after a virus (which IS contagious). However, often I have gotten that thick, yellow/green mucous at the end of a cold without infection. If you develop a fever or worsen in symptoms, call your doctor as a secondary infection may have set in. Otherwise, you are suffering a virus that is contagious. Wash your hands frequently and those around you sould do so as well. Wash down door knobs, tv remotes and phones. good luck and hope you feel better
Oh, and double your fluid intake to keep the 'stuff' moving well,
if you have what's going around here in Florida, it's a viral infection that affects the sinuses (the cause of the bleeding and mucous) and yes its infectious. Even worse, lasts up to 6 weeks!