I have pain when standing on one leg, even putting on my pants, what is a good exercise for overcoming and strengthening this area?

Strengthening probably isn't a good idea right now.

It sounds like a strain,any additional pressure on it would just strain it further.

What were you doing when the pain first started?

This has been going on for about 6 months. Perhaps driving a lot is the only thing I can remember. I don't recall how it first started. The point is that it stays about the same, but is extremely painful when carrying something up and down stairs.

I just looked at this site,check it out,it might answer some of your concerns.

Your Health - Quadriceps Strain

Then see a doctor!