Getting pregnant on the pill

Has anyone fell pregnant while on the pill? I’ve been on regivedon for nearly 2 years and today I had brown spotting like the size of a 5p twice and then red spotting the same size TMI and now nothing? I’m wondering if it’s implantation bleeding? The last time I had brown spotting I was pregnant with my son 3 years ago but because I’m on the pill I don’t know what to think so wondered if anyone had anything similar? Also been so tired and slightly sore in one boob