It is probably gas and will go away on its own. If the pain stays more than a few days or if it gets worse, you should go see your doctor.
I would suggest trying gasX or something similar. If that doesn't help, it may be a good idea to see your doctor. Watch for fever and blood in bowel movements. If neither occurs, may just be gas.
I'm not sure if you are a woman, but if so, an ovarian cyst is a possibility as well. I get those from time to time, and initially can be hard to tell if it is gas, or if it is on the right side, a possible problem with my appendix. Gas is another possibility - try a simple solution first - GasX or Ovol. If it still hurts tomorrow, or gets really bad, I would think about getting it checked out....
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It could just be due to indigestion or slight food poisoning. Take a lactobacillus preparation, plenty of fluids and light diet and see. Pain and discomfort on the lower left side of abdomen just below the ribs and to the left of navel can be due to several causes such as Crohn’s disease, colitis, 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.
Please consult your PCP for primary examination followed by proper referral as confirmed diagnosis is not possible on net.