Depo/implantation??

So I have been on the depo injection a year come May 8th which is when our last baby was born, have always had them on time even early so never thought I’d be writing this🤣 this is the third time over 9 years I’ve been on the depo for contraception and always worked fine for me before! It’s been fine again this time round absolutely no problems whatsoever, however.. the last 2 nights I have had the odd back & front cramps mainly one sided, and a couple of the tiniest spots of blood (very light pink / some pale brown) only when I wipe and it hardly been visible! I know that irregular bleeding or spotting is a massive ‘side effect’ from this contraception but it’s not happened to me before either this time round or over the last few years whilst being on it. I’m panicking in my mind that it could be possibly implantation spotting which I had with 2 out of 3 pregnancies, I understand this is a rare occurrence! But has it happened to anybody else?I also do not have periods whatsoever on this.