I Was In A Car Accident 4 Weeks Ago, Ended

I was in a car accident 4 weeks ago, ended up with a ruptered spleen level 3, contused ribs. No breaks or fractures showed in chest xrays or ct scans. I'm finally feeling relief from the spleen area, but recently started to feel sharp continuous pain on my left side of my back below my ribcage. Hard to sleep on my back unless I have a pillow under my left side, VERY painful when I yawn, sneeze or take full deep breathes. I feel pain when I walk sometimes as well. I thought at first this was just muscle pain, residual pain from trauma, but it's been a week now and has gotten worse. What could be causing this?