i d like to note i m a cross country runner.about a month ago i started to feel like i had no energy while running.i thougt that i was iron deficienct since a lot of female long distance runners become iron deficient.After awhile,after i started taking iron,i still felt really fatigued,to note that it wasnt the right type of fatigue,and feeling like i was about to past out every run.To add that i progressively got slower and started getting chest pressure while running.Now it s just difficult to run,with my chest hurting while running and being fatigued and ready to pass out.I m a 15 year old girl.recently i heard a pop on my upper left rib cage when i was stretching .i found that kind of weird.