Knee pain, medial aspect, both knees

I have rather suddenly developed acute knee pain on the inside of both knees. Very painful to push on, little or no swelling, a little tight when I draw either foot up behind me, aggravated by jogging but sprinting on the balls of my feet doesn't hurt. I'm 45, a former minor league baseball player, never caught, no instability. If I rest and ice for a day or two it goes down to minor soreness. Biking, elliptical training and stairmaster don't aggravate it, running does. There is a slightly boney prominence on the inside of both knees and if pushed on is excruciating. No insurance right now so I would appreciate ideas as to what this is. Thanks