What Causes Discharge With Blood Stains From Vagina While Having Copper T?

i've been using the copper t for 3 years now and my periods are really long. It starts with brown discharge for about 5 days then the actual bleeding for 5 days and again the brown dishcharge for 5 days. But this time around after i was clear of the 5 day brown discharge i found the discharge from the vagina had blood stains. I'm very sure that its not the blood from the periods. Could anything be wrong. I'm 29 yrs old, have a 3 yr old kid.