I am having extreme pain in my solar plexus area that radiates to my back and it only seems to go away when laying on my back when with knees up. ?

The celiac or solar: plexus is a complex network of nerves located in the abdomen near where the celiac trunk, superior mesenteric artery and renal arteries branch from the abdominal aorta. Pain from that area radiating to the back is a classic symptom of pancreatitis, but could also be pain from stomach or duodenal ulcer, gastritis. You need to see your Doctor or go to Urgent Care. Good wishes:)