A Difference between 'Due to' and 'Because of'...

My Question: Chachu what is the difference between 'due to' and 'because of' ?


My Guruji's Answer: 
X got admission because of Y. 
Y is due to X for his admission.
The difference is that of a giver and a taker.


Question: Then Chachu " Is it I was down due to pain or I was down because of pain"?


Answer: 
You are both, the giver and taker here.
You are the reason/cause and effect for pain as u decide as to have pain or not!