Helllp!! Implantation bleeding or Old blood/start of period?

Sasha • Been together 6 years ttc our first! ❤️
So here's the story... Yesterday I went for a wee and wiped (as you do) and there was a tiny bit of brown discharge but it wasn't like a clear clot it was more like spots it was only a tiny bit so I only could notice it of I wiped... I had a bath then I started getting a sharp back pain in my right side on my back and sharp pains (not like period pains.., less hurtful but more intense) in my lower abdomenal area on the left side,..I had the pains today but I haven't noticed any discharge/spotting. The last two times I had sex was on 16th and the 4th or august and it's the 24th today... I have irregular periods so my question is does this sound like implantation or old period blood to you girlies? Any help would be much appreciated! P.s my app said I should've come on this week as well my last period was on the 24th-29th of July :)