My Husband Has Developed Pain Above His Left Hip, Below

My husband has developed pain above his left hip, below his ribcage. He said it is a dull pain which feels like swelling inside. He has a history of kidney stones...but has had no problem for years. He also said this feels like a different pressure and location.
He has been weak and sleeps and stays in the bed or recliner most of the time. Not eating much today. No fever.
The pain was severe enough to wake him. He asked for a muscle relaxant. Soon went back to sleep.