It's just an anxiety attack due to mental factors (i.e. thinking about it too much or being subconsciously scared/freightened). I got this the first time I did my injection except I didn't pass out and I snapped myself out of it.

After a few times of getting used to injecting, the panic attacks go away. BUt that's all it is. It has nothing to do with your gear or anything, it's all mental/psychological.