Hi,
Welcome to the forum. I am really glad to help you out. The normal menstrual cycle length is 28 days but can vary from 21 days to 35 days and this is considered to be normal. Frequent menses (cycle less than 21 days) can occur due to pelvic inflammatory disease, sexually transmitted disease, endometriosis, fibroids, cervical polyp, birth control pills, stress, exercise and hormonal imbalance.
Considering your other symptoms as well, you need to consult a gynecologist and get yourself thoroughly examined to diagnose the cause of irregular periods and start with the treatment. you may need to get certain investigations like ultrasound uterus, serum HCG test for pregnancy and hormonal panel done.
I sincerely hope that helps. Take care.