What do brown period blood for months mean? first started after having gallbladder removed recently. have iud for 4 years never happen before.

Possibly normal: The timing is probably coincidental and It is unlikely the gallbladder surgery had anything to do with this. You are not clear whether you are simply seeing brown blood with your period or if you are seeing persistent brown blood. If the former then there is no concern, just very light periods. If the latter then it is worth a trip to your gynecologist.

Old blood: coming out of vagina. The timing is probably coincidental. The brown blood is likely just old blood that is now leaving your body. Likely this will pass with time. But if you have lower abdominal pain, tenderness or a fever (>101.3F or 38.5C) then I would be concerned because from that point all bets are off , brown discharge should be looked at as sign of infection.