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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. All these can also cause dizziness, nausea and fatigue (may be due to low grade fever). Please discuss this with your PCP. You will need blood, urine tests, CT scans etc to reach a diagnosis.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!