Spotting

Last week at the doctor I tested positive. I didn't want to test but because I was a day late, they had to test before prescribing something for me, for what I was there for. Anyways, we are excited. I miscarriage last June. I have 3 boys, this will be my 4th pregnancy and honestly I can't remember ever spotting through all my pregnancy. Today at 5 weeks, when I wipe after peeing there's VERY light, not red though but rather brown/reddish, I can't really figure out the exact color but its definitely not RED. I'm worried if it is really implantation bleeding or could it be another miscarriage on the way? I wasn't planning on visiting the doctor atleast until I'm 8 weeks but now I guess I have to go there tomorrow.