I'm so confused.

I'm gonna you back story here. My last period was 06/15/17. My cycles are usually very irregular ranging between 35 and 42 days.On 07/02 i started spotting light pinkish red. On 07/03 it turned brown and my boobs started aching. On 07/04 I started spotting red again and I had a headache. I'm an emotional wreck and nauseas. I am really trying not to get my hopes up. I just think it's weird because I'm bleeding on cycle days 17-20. I think based on keeping a calender I should be ovulating next week. So is this implantation or something else?