Hello i have read your query. Lumps or growths on the roof of your mouth are often benign and easily treated but sometimes can indicate a more serious condition. lump on the floor of mouth can be due to few conditions like: Torus Palatinus Oral Cancer mucocele you have not mentioned your age. do you have any oral habit of smoking or intake of alcohol. Sinusitis is inflammation of the air cavities within the passages of the nose. Sinusitis can be caused by infection, but also can be caused by allergies.symptoms include sore throat, headache, ear pain, fever, cough. i dont think the lump in your mouth is connected to your sinus problem. i wud suggest you to visit a dentist and a physician for sinusitis. Hope this ans helps Regards Dr. Shesh