My 2nd toe next to the big toe on both feet is red and a bit swollen. It hurts, and is quite sensitive. On one of the toes I noticed something that looks like a sac of liquid underneath the toenail. I am currently in tennis season, and am practicing long and hard. I am sure tennis is the reason for this, but I would like to know how I can prevent this from happening? Would a simple shoe change be helpful?