Thanks for your query, I have gone through your query. The bleeding in the oral cavity could be because of the gum infection, or any cuts in the oral cavity or pulp polyp or any bleeding disorders like idiopathic thrombocytopenic purpura. Since you are giving history of poor oral hygiene, it looks like the bleeding is arising secondary to gum infection. The yellowish color of the teeth can be secondary to the deposits like calculus. Consult a oral physician and get these things ruled out. Get a complete blood investigation along with INR to rule out the bleeding disorders. If any gum infection then get your teeth cleaned and use topical gum astringents like stolin gum paint. if pulp polyp is there then get it root canal treated. If bleeding disorder is there then consult a general physician. A normal or regular dentist can treat the gum infection and make the teeth appear white by doing scaling and polishing. I hope my answer will help you, take care.