Thanks for writing to H.C.M. for your query.
I have gone through your query regarding sore gland knot in the roof of your mouth, I am suspecting most probably it is-
(a) Ectopic salivary gland
To manage this we need these investigations-
(1) C.T.scan of paranasal sinuses
(2) Culture and sensitivity of throat swab.
(3) FNAC from knot.
After this a thorough examination and clinical co-relation with investigations will help to reach to a final diagnosis and that can be accordingly manage.