What can cause sharp chest pains and discomfort while breathing?

I've been having difficulty breathing for quite some time, especially since moving to SC and when I had gone to the doctor about it, they tested me for asthma, to which I had did although slight. An dhere recently i've been having chest pains and problems breathing when I'm trying to sleep. I use my inhaler but it doesn't seem to work and I can't get comfortable no matter what position I sleep in. It hit me hard when I has gone outside in the heat to help my mom cut the grass and I couldn't even do much before my chest started hurting and I couldn't breath so my mom sent me back inside. She even told me to go to the doctor to see what they say. If anyone could help me, please. I don't know what it is but it has me a bit scared that I can't and even don't want to go to sleep at night.