Loss of Control in left side pectoral muscle

my left side pectoral muscle is only about half the size of the right.  it was not like this before, but i am big on weight training and i was experiencing some asymmetry with the pectorals (with the left side), so i went to try and isolate the left side only, and then it soon after just stopped working properly as in i cannot get a proper contraction.  whenever i go to train, the left side does not pump up with blood at all, and i can't feel the contraction when i try to contract it otherwise as well.  i am guessing this is due to some sort of nerve impingement?  im not sure what to do about this, and what exactly it is for that matter.  please help?  im desperate.  this has been going on for a few months now.

[abhijeet v ghosh]

Hello rakumoni
well don't think about nerve impingement as at this stage as it will be associated with some sort of sensory problem or paresthesia, etc. Are you under a proper trainer for the weight training purpose? If not, then you need to. Don't get worried or desperate as building a muscle is under your will power. Just get proper trainer and all will be taken care of.
Do ask me more if you got more questions.
thanks
abhijeet