How can I overcome the breathing trouble while meditating and increase concentration? At  certain point of meditation,I feel like I can't breathe properly as in the beginning of meditation(lose of oxygen) and thus I stop meditating and try to get oxygen into my brain.
I do no know why this is happening or how to overcome this condition. 
Is that not a correct way of meditating? Or what am I doing is wrong ?Or do I have to push through?
It is difficult to answer your question due to not many facts. However, the impression is you are suppressing your mind or pushing your forehead down into your body; making your mind &amp; forehead/forebrain rigidly still; and, at the same time, pushing your air/breath/outbreathes out; clenching your jaw &amp; emptying the lungs &amp; nostrils of breath. 

In Buddhist meditation, the face should be relaxed and the mind/brain bright, awake &amp; open. The Buddha taught to start meditation by establishing awareness in front of one's face. Possibly do some practise keeping your eyes gently open and keeping your face &amp; jaw relaxed. Buddhist meditation is the practise of "non-attachment" rather than forceful suppression. 

It is probably best to visit a Buddhist/meditation centre and talk to a teacher.