Thanks for writing to H.C.M. for query.
I have gone through your query regarding painful lump in neck which is there for few days than it disappear and after one week it reappear this put suspition for these possibilities-
(2) Enlarge lymph
(3) Sebaceous cyst.
(4) Thyroglossal cyst
These above listed diseases are having their own clinical features but to confirm it you are advice for these investigations-
(2) F.N.A.C. from neck lump.
By the help of examination and above two investigations one can diagnose the disease which than accordingly manage.