DR. FEELGOOD: Blues master Dr. John concludes his 2004 world tour with two headlining dates, tonight and tomorrow, at B.B. King’s Blues Club. Known for his spooky swamp rock and piano rolls borrowed from Professor Longhair, the gravel-voiced singer will play a career-spanning program. He’ll “Walk on Gilded Splinters” and croon the chorus of “Iko, Iko” and other New Orleans classics in this musical gumbo. There will be two sets each night, at 8 and 10:30. B.B. King’s Blues Club, 237 W. 42nd St. (between Broadway and Eighth Avenue). Tickets are $35 and are available through Ticketmaster outlets, (212) 307-7171.