Implantation bleeding

So, my period was late and I took three pregnancy tests that all came out negative. I got my period Thursday but also started the pill same day(was on it But stopped because of side effects few weeks prior but pregnancy scares are too scary) I also started feeling extremely nauseous and have been throwing up since Thursday. Now my period has been extremely weird. Usually when it gets here late my body seeks revenge and I feel cramps and pain And heavy bleeding. This period had minor cramps and very very little bleeding and today I read an article about implantation bleeding and have all the symptoms idk what to do. And I'm if I'm being paranoid and this is just from the pill.