Mouth and throat related. Care of early?

I have a open tooth with no capping, (left jaw molar crown isn't placed post root canal), a damaged crown on the right molar and a filling to be done on the upper molar. Recently I have been feeling a bit of pain on my throat (right side near Adams apple). It happens sometimes and is usually accompanied by pain on the right jaw all the way to the neck as well. Recently I have also developed a small ulcer inside my mouth between my upper lip and nose. I am a bit confused about what is happening to me, please help. Can it be cancer or is it a dental anomaly which should be taken care of early? Smoking has been frequent since last 8 months, averaging 3 cigs a day. Before that 2 cigarettes in 1 month for 4 years.