I read about pleurisy. But, I'm not having problems breathing. I'm just having chest pains and just a, I don't know, tightness in my chest. Could this be from binding?
Could be if the pain only started when you began binding. I used to have the same thing until i switched from Underworks to gc2b binders and now have no pain or difficulty breathing at all. Another problem is binding can cause your ribs to crack; but that's in rare circumstances were you bind with ace bandages or the cheap Chinese binders you can get on ebay; and continuesly do so for years.
Are you sure you have the right size as well? Not only does a size that's too small hurt your ribs but can make you look less flat.
Breathing problems, fluid buildup/retention, permanent disfigurement to the breast tissue, shoulder/back/chest pain, broken/bruised ribs, etc.
The percent chance of each varies, and is affected by whether or not you're binding correctly. If you are sure you are wearing the right size and you are not wearing it too long, then you should probably see a doctor to rule out other issues. Chest pain and tightness generally isn't a good thing.