What Are The Side Effects Of Intrauterine Device?

i have the implant and have for maybe a year now and since i had it done i haven't had a period but this morning i noticed i had blood in my underwear and i have had sex since having the implant but never had a period and when i cam on this morning i had longish like jelly looking thing mixed in with it , plus my blood is not red it is brown like it has been there years.
please could you help me