hi.
'obsessive' behaviors are called compulsions, and are seen as a part of obsessive-compulsive disorders. burping comes from stomach, and not from lungs. so if you are sure its a burp, its unlikely that you have 'early lung cancer'. the
swollen lymph nodes and dry tongue might be secondary manifestations of an open
mouth breathing. also, too much deep breathing might cause
hyperventilation which makes you feel giddy, fatigued and sometimes nauseated.
however, there is no alternative to a physical consultation with a doctor.i believe you should consult a qualified physician near your place. he/she should get you evaluated adequately for any underlying organic cause, and can arrange for appropriate referral thereafter, in case you need any.
hope this helps.
Dr. A. Rao Kavoor