All the thick padding in them that make them so comfy, also make the shoes tight. You could just be more susceptible to in grown nails. Some peoples nails are more rounded. Does anyone else in your family get them? Do you play sports? Once it heals to the point of no open wound, you can soak your foot in hot/warm water with epsom salt. It will draw some of the infection out. Also, one your nail starts growing back, soak it a few times a week, because when it's growing back you are at more of a risk of developing another one.
My problem was wearing skateboarding shoes,converse,and cleats. I was in them all day at school, either went to skate after school, or to a friends, so I would not take them off until late at night. The last two times, I did not play football anymore so it was defiantly from the shoes I was wearing. They were not to small, I always had a thumb length between toes, and tip of shoe. They are so thick to protect your feet from skating, that it just squeezed the hell out of my feet.
Edit- I don't think so. The nurse said I couldn't have anymore medicine because they gave me as much as they could. I turned pale, and sweaty.Then they said I turned green before I got sick. My mom was in there every time until they started cutting. She couldn't handle all the blood.