Implantation bleeding or just early period?

Tree
So I have a regular cycle of 28 days. I started my period on July 10 and it was regular like always. Well on July 31 I woke up and I had light spotting. I would only see the small spotting when I wiped I didn't even need a panti liner. On Sunday it was a little more blood but it was bright red.. So on Monday and Tuesday it was still going.. No heavy bleeding.. And today just light spotting. 
I just want to know if this has happened to anyone else. I am very light headed, exhausted, and very tender breast. Someone please respond lol Oh and I have taken two test and they were both negative.. My next period should have been here on August 7