Why did it start to hurt to breathe after a lap and a half? Okay, so today I had to run a mile at school. I was fine until about a lap and a half. I started to not breathe right. My sides hurt when I tried to breathe, everything in my ribcage felt like it was going to explode and that also made it hard to breathe, and then I started to taste blood . But when I spat out in a sink, I saw no red coloring. I started off at a good light-medium paced jog. I tried to jog after I got the pain but it just made it worse so I kept on walking. My friend said it could be asthma , but I don t think I have asthma at all. It hurt to an extreme to where I was going to cry. Soo..Anybody know what the heck this is?? :(