What Causes Frequent Urination,lower Abdominal Pain And Vaginal Bleeding?

I am 38 and since my period 2 weeks ago I have felt the need to urinate more frequently. I have had some pain in my lower back and abdomen, though not consistently. This morning I had some light vaginal bleeding. I have experienced these bleeds before and had a smear which revealed nothing, though that was over 3 years ago and was told it was due to stress at the time.