abnormal period ?

hi so i think i started my period this month but it’s not really my normal period. my bloods been more brown but kinda red and my flows light but heavy enough that i need to have a tampon and pad on. it just isn’t fresh blood i guess. so i’m not sure if i’m starting my period or it’s just old blood. it’s been like three days of the same thing and back pain and cramps soooo idk help?!