Pain in upper left stomach and some in back earlier today. then all the sudden had the urgency to poop it was liquid diarrhea. should i be worried this could be serious?

If it happened just once, it was likely due to something you ate. If it continues to happen, then you should see your doctor to find out what it is due to. The only way to treat something is to diagnose it first. A GI doctor may be needed if it continues and the diagnosis is unclear. But, if it occurs just once followed by normal, formed stool, it is likely a dietary issue. Good luck to you!

The pain in the upper left stomach area and in the back area followed by diarrhea is likely intestinal pain initially caused by the diarrhea that came later. You need to avoid dairy products up to at least 24 hours after the diarrhea subsides. Only drink clear fluid (fluid you can see through) until the diarrhea stops. Diarrhea can be serious, if persist more than 48hrs, see a physician for tests.