Implantation bleeding or Af? TMI

Mysha
So I'm 15dpo and 2 days ago I started what I thought was my period. It was very light and brown with EWCM mixed in it. I used a tampon anyway. I had mild cramps like a period but when I changed the tampon it was almost clean with brown old blood an CM it stopped today and my periods usually last 5 days not 2. Help!!