Hi welcome to Health care magic forum.
Thanks for calling H.C.M.
As you describe your problem is E.N.T. problem, so you should consult an E.N.T. surgeon for diagnosis and treatment.
Possible causes could be allergic rhinitis
, adenoides, papilla of trabiculae. etc. There is very very little possibility of cancer.
You may have to go for M.R.I, besides other routine tests for confermation.