Inability to concentrate may be because of many issues.. associated sypmtoms along with poor conc helps us to diagnose better. U said that songs always run in my mind. Is it cause u always hear them or your hearing them when your alone when nobody is around. If thi problem is effecting your work knifly consult a psychaitris
Next Steps
Tips to improve conc,
Good sleep
Proper dietary habits
Regular exesice or yoga
Away from smoking and alcohol.