Hi Marye,
I read your thoughts and felt pulled to reply, though now that I open the comment box, I'm not sure what it was that I wanted to say...

Something in your words resonated strongly. I know that feeling of discomfort when confronted with beggars or homeless people, and your thought about this discomfort stemming from a feeling of helplessness kind of made a light dawn on me. Sounds as though it fits. Or is at least part of it.

Thanks for the insight.

So maybe I can in return give you this -

As for feeling small and powerless, unable to make a difference, here's something that I read a while ago, something that also resonated strongly, and something that picks me up every time I feel small and powerless and unable to make a difference:

If you think you are too small to make a difference, try sleeping in a locked room with a mosquito.