Blisters on underside of toes

On the 2nd toe of both feet I have blisters  (not on the pad, but the joint where it connects to the foot).  I've been on the elliptical for 60 minutes most days (90 minutes yesterday) and now I'm getting blisters.  Not sure if it's the movement, socks, or shoes.  I can feel it rubbing while on the elliptical.  Ideas on how to combat this?