Hi, Eshwar
I am sorry it's so hard on your dad this time around. Is the mouth infection fungal, bactercial or both? My husband was on the anti-fungal and had a tetracycline-base swish-and-spit at the same time. He was also prescribed something call Stamford's #7 as the tetracycline-base stuff didn't do too much.

You mentioned that you feel helpless ... that is such a horrible feeling. There is an American (I think its American, the Canadians and Aussies will let me know if I'm wrong :-)) idiom that I am not sure if you are familiar with - being "in his corner". It comes from the sport of boxing, and refers to the trainer being in the fighter's corner to help him through the match. You are in your father's corner, helping him fight the beast, supporting him and cheering him on. You may feel helpless against disease and pain, but you are a very great help to your father's spiritual and emotional well being. It is a blessing to you to be able to give this help and support, and a blessing to your father to receive it.