Help!

I have irregular periods so just ignore when the calendar says I should ovulate (that’s just an estimate). I had my period at the beginning of this month and on the 22nd I had half a day of light pink/brown spotting when I wiped. Nothing since then. I thought I was just getting my period early because that’s how it usually starts and they are irregular but now I’m nervous. Could that have been implantation bleeding? We aren’t trying and I’m assuming it’s too early to test?