I have been sick with a cold and coming and going stomach ache here and there. I don't feel that sick on a day to day basis anymore but when I run a race or run hard in practice it is hard for me to breath, I feel a lot of phlegm in my throat and snot in my nose, my stomach starts to hurt, and my legs can't move fast because lack of oxygen getting to them. I am worried because I am in my cross-country season and I want to feel good in my races. What do I have and what can I do?