Periods on implant confussion

My twin sister has had the implant in for a year now she has never had a period while she has had it In she thinks she might also have a uti but not sure she had a bit of blood on the toilet paper but then she went to the toilet again recently but there was more blood when she wiped but it has clots in it the blood is only on the toilet paper and is not on her clothing does anyone know if this is a break through period or could be uti symptoms she is going to see how it goes tonight and ring the doctors on Monday