Leg injury - should I ask for a 2nd opinion?

Over the past 4 months, I have fallen on my left knee a total of 4 times, the first time was bad, but not enough - so I thought to go to a doctor. Then about 3 weeks later I fell again on the knee, then 4 weeks after that again, and finally about 3 weeks ago I fell quite badly on the knee straight onto cement. Each time very different circumstances and rather unavoidable - just freaky. I have a somewhat 'crooked' right leg which lends me to falling onto my left leg. BTW: with each fall I never got a bruise just terrible pain if I touched it or my shin and there was improvement within a week and almost completely better within about 3 weeks.

This time I waited about a week and 1/2 as was more pain and zero improvement, it just felt different. I went to the doctor a week ago and she said just to take advil for three days - no improvement. I don't feel that this has been taken care of properly, but not sure if there's any point in asking for 2nd opinion or getting X-rays at this point

it seems to me that you're having some major instability in your knees so i would suggest getting an mri instead of an xray to see if your ligaments and tendons are ok. you should still continue with the advil for the pain and try not to fall as much and maybe you should do some icing on your knee to see if that helps but there no other way to tell you what else is wrong but what did you do to fall on your knee like were you playing a sport or just randomly fell. go see a different doctor and get their opinion on it.

Get a second opinion!

Doctors are wrong often enough to carry high liability.
I have studied this and have been amazed at the mistakes.
You could be one.

I myself went to a doctor for a what I thought was a broken rib.

The X-ray technician not only told me it was broken, but he pointed right to the crack. He had done the X-ray thing for 28 years.
The doctor told me it wasn't broken. He had 3 years experience.
I then asked to see the x-ray as the doctor was still with me, and when I pointed to the spot the x-ray technican showed me....Well, the doctor suddenly changed his mind.

He should have been paying me for my own diagnosis.

You should get an X-ray. It's a possible crack of the bone if the pain is great and inflamed. Advil is not a solution, and try to avoid using the leg for a time.