Hello and welcome Answer to your question is Yes, birth control shot at times may cause irregular periods. Looking at your description it might be related to hormonal imbalances, PCOD, stress and anxiety, infection or inflammation of the genital tract. I would advise you to consult a gynaecologist according to your convenience, for an ultrasound and hormonal study to find out the underlying cause and further course do action. Meanwhile maintain good hygiene, have plenty of fluids to maintain good hydration and urine output. I would also advise you to take iron and multivitamin supplements to correct the blood loss in the form of excess menstrual bleeding. Hope I could answer your question. Best wishes