Hello, I Stopped Birth Control Around New Years Day, Had

Hello, I stopped birth control around New Years Day, had a normal period, and haven't had one since. I have been sexually active with my boyfriend. The other morning I went to the bathroom and noticed spotting (pink, only on the toilet tissue) which lasted a few hours every time i used the bathroom. The second day, I had a light brown discharge-like substance in my underwear (about a dime size), and today I have the pink spotting again only a bit more heavy. I'm worried that this could be implantation bleeding or something serious such as an infection.