Women have you ever had something similar?? Or is it normal ?

Yesterday I thought my period had started because I had spotted So I put a tampon but when I took it out it was mostly brown/mushy. I did have a little bit of red but nothing compared to the brown. The second one wasn't in as long so it was only slightly brown so I decided not to use anything overnight and it was fine nothing came. Today eventually in the afternoon I spotted so put a tampon again and the same thing happened with the brown. When I wipe I don't see anything. The tampon is the only thing coming out weird. Is this old blood? Ever since I got on the pills about 8 months ago my period has been super light. I don't know if this has anything to do with it but yesterday morning I took two birth-control pills because I missed the one from the day before but it's not the first time I have done it and also I had blood taken out by the doctor that morning.