Hey mommies I really need some advice

August and September I came on the 29 and lasted a week then October started the 24 lasted 3 or 4 days then November came on the 25 lasted 3 days now this month started the 26 and having horrible pains my vagina hurts my stomach hurts at the bottom near my pelvic this been going on for a minute then my back is killing me and I'm always feeling nauseous or don't have a appetite

So August and September I had normal periods and October November and now they r different and the symptoms I'm having

What up