Serious back pain

Cynthia • 20, engaged and ttc.
I have had serious back pain for like 2 or 3 weeks. But specifically in this one area like circle shaped in my lower back to the left of my spine. I usually get cramps pretty bad before my period and have had nothing but slight cramps which just feel like ovary pain . I was one day late on my period this Month and this is only my second day. It's also usually very heavy the first 2 or 3 days and is not this time. Mostly just brown and red blood . Been very moody and angry lately, breaking out with acne and serious fatigue, also habent realky had an appetite lately. Like I'll be hungry in the morning but the rest of the day I have to make myself eat. Basically I'm asking for advice on whats going on and possibly if theres.something I could do for the back pain. I've been taking midol and ibuprofen but it's just not working.