Sneakers, Shoulders and Creatine

Hello all, I started training again a month ago. I used to train at home while in college and now I am taking boxing/fitness classes, taking some technique and light sparring. The main problem I am having is the shoes I use to train. I have a pair of running shoes and my feet move inside them, causing me pain. I tend to take them off and continue training with my socks on. I also tend to get plantar fascitis very often. So the question. If I were to get new sneakes what would you recommend, running shoes, cross training or basketball high-tops. I am not ready for boxing shoes. Additionally my shoulders are getting pretty sore and fatigue during the workouts (as if I was lifting weights). After a month I expected them to feel better. Someone recommended taking creatine before workouts. Any suggestions? Thanks, E.