Sore cheeks, nose, painful upper teeth for the past couple of weeks. feel i've some sinus symptoms. main pain above a root canalled molar. connected?

Perhaps: All your symptoms might be related to a sinusitis. However, pain above the rct tooth may not be. We can't confirm or refute that. You will have to see a local dentist to evaluate the cause of all your symptoms.

Pain above teeth: The location is right for possible sinusitis relation, however, given past hx to teeth in that area of root canal, as dr sandler noted you should have it evaluated asap. Aches and pains are normal for the most part but lasting discomfort is not.

Molars and sinuses: "Symptomatic" molars in the upper jaw often prompt root canal therapy when underlying sinus problems are in play. Root canals may fail to 'cure' the tooth infection, or the instruments or materials may enter the sinus during tooth treatment promoting infection. All may be "quiet" for some time, even years, then flare up with symptoms. See an oral surgeon for evaluation and discussion of options.