Upper left abdominal pain below the ribcage, that lasts for several hours and is made better by sitting or bending forward, is suggestive for pancreatitis, or inflammation of pancreas.
Gallstones and prolonged alcohol use are the most common causes.
There are several other, less common causes of acute pancreatitis, like certain medications (steroids, diuretics), high levels of triglycerides in blood,
high blood calcium levels, surgery or trauma to the abdomen, infections such as mumps.
Upper left abdominal pain that wakes one from sleep can result from peptic ulcer, too.
You should find a way to see a physician!
Best wishes!
Marija