Implantation or low progesterone?

Speaking mainly to ladies who have short luteal phases- i started having light brown dc on 5dpo. Never needed a panty liner, really only get it if i check my cervix or wipe. Its been the same 6dpo and 7dpo, not darker or redder. Cramping all 3 days. Does this sound like low progesterone? Beginning to consider implantation.