What Causes Heavy Discharge After Inserting CU T?

hi doctor, i have inserted CU T in june 2010. after one month i had heavy periods and i consulted with my dr and prescribed medicines for three months. but after that i had normal periods and i didnt had that medicine. on last November had little brown colored white discharge and i went to a gynecologist.she told me that vaginal infection is there Cu T is safely there. for infection she prescribed me antibiotic and vaginal tab. now from last two months discharge is more and periods is getting longer than previous months.is this will be the same infection caused? should i consult with a gynecologist?