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There are various causes for left lower abdominal pain. I understand you have undergone several investigations. Please go through this and see if something was missed . Pain and discomfort on the lower left side of abdomen just below and to the left of navel can be due to several causes such as Crohn’s disease, diverticulitis, infection in kidney, kidney stones, adhesions, polycystic ovary in females, IBS, constipation, and an abscess in rectus abdominis muscle or psoas muscle. Since you do not have a lump or a tender hot spot, in all probability it is not a muscle. It could also be a periumbilical hernia that has got trapped resulting in small bowel obstruction or mesenteric ischemia. There is a possibility that there is a stone in the urinary system. This also causes pain that can be felt in groin and hip area.
Since you have white and red blood cells in urine, cystitis, kidney or urine infection and stone in the urinary system should be ruled out first. A CT scan of lower abdomen and pelvis should be done.
Hope this helps. Do let me know if there is any thing else and keep me posted. Take care!