What Causes Sharp Pain In The Spine While Doing Yoga?

I've been doing th excercise program P90X for three weeks now. While I was doing the Yoga portion I was going down for a push up and on my way up I felt a sharp pain in my spine between my shoulder blades area. I was able to rest five minutes and continue the workout but when I finished the pain was coming strong and I felt numbness from my left shoulder blade throughout my armpit and towards my left pectoral. That night the pain was excruciating, I had to take Motrin and had some left over Flexeril. My spine area still hurts like if there were a pinched nerve and my numbness under the armpit has not worsened or improved. I literally cant feel anything superficial on my armpit unless I pinch the area. Unfortunately dont have insurance and cant afford doctors..it's been like this for 4 days now. Should I wait to see if it gets better or should I go see the doctor?