Early period

My husband and I just started our ttc journey, and I've been very discouraged getting my period every month. This month was a lot different. Aunt Flo decided to visit me a whole 10 days early. I've been cramping like crazy (not painful, but very lightly) and my back has been hurting very badly. I have lower back problems and at first thought it was just that, but the day before my period came it was a tight spasm. It's been about two days and it still feels this way. I'm a little concerned because at first I was thinking maybe it was implantion pain, but my flow is a normal flow color, not implantion color. I'm just a bit concerned because I've never had a period come as early as this. Maybe a day or so, but not a whole week and a few days. Just wondering about it, and if anyone else has experienced something like this before.