TMI;.implantation? 4 weeks since Mirena

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Could this be implantation bleeding or the start of a period? Started yesterday or Friday afternoon(can't remember) only when i wipe and the slightest on a panty liner. Had my Mirena removed 4 days ago, no period since. Have had unprotected sex using pull out method but he did come inside April 1st. Thoughts? If i don't bleed when should i test? (Also its more of a brown in person;not red)