Why am I having trouble breathing?

For the past month or so, when I’m sitting in class, my whole body would get this ‘tight’ feeling, and I’d have trouble breathing. I have to get permission to go to the bathroom to catch my breath, or I would put my head down. I’m not sure if this is asthma though. My little sister has asthma, but she hardly ever needs her inhaler (spelling. sorry), and my grandmother also has asthma, but like my sister, she hardly ever needs her inhaler. Anyway, today I was sitting in class, and I all of a sudden started breathing really heavy. I put my head down, but got in trouble by the teacher, who made me put it back up. I tried telling her I couldn’t breathe, but there was only ten minutes left of class, so she told me to try to hang on through the rest of class. My head starts to feel heavy, I get dizzy, and of course, I can’t breathe…this didn’t only happen today, as I said, it’s happened often in the last month or so. Some other things that happen are my eyes get red, my head starts to hurt, and I feel too weak to stand up or move my arms. I was practicing softball earlier, and found I had trouble throwing the ball, swinging, and after I ran to catch a ball, I couldn’t get my breath back..my dad saw this, and he just told me to stop for a whlie. I came home and took a shower (cold..because it was hot) and had some trouble standing up in the shower. I’m not sure what’s going on, but right now I’m fine. A few people at school have told me it was a panic attack or anxiety attack..does anyone know why I’m having trouble breathing?