Hello, First of all, you undergo one blood test for beta-hCG to rule out conception. It is more reliable than home pregnancy test. TVS scan gives additional information. Other reasons are stress, hormonal imbalance, pelvic infection, irregular diet habit, over wt etc. Following initial test result, you consult with gynecologist to proceed other investigation. Take suggestive measures accordingly. Maintain genital hygiene properly. Avoid stress and control body wt. Take some muscle relaxant gel to reduce back pain. Hope it helps for you.