If you haven't serviced the BB in many months, just go ahead and clean and regrease it.

Release chain tension; remove cranks; soak BB spindle, cups, and bearings in degreaser; wipe all parts down and scrub hardened grease particles off; check for pitting by running the point of a pencil over the places the bearings contact the cups and spindle; grease the hell out of EVERYTHING; reinstall BB but don't overtighten adjustable cup (this will create undue friction and cause the spindle to spin slowly against added resistance); blah blah blah.

Good luck.