confused.

so I'm on the implant and I had sex on fathers day and sorry for the tmi but after he had came in me he started fingering me and pushed his finger into my cervix a bit. well 12 days later and I've been nauseated for a few days and have had heartburn even though I've had nothing to give me it. I tested yesterday and it was negative but it could've been to early. what do you guys think