Stop in for a cup of coffee

I agree with Ddaddy the IT band. I experience the same symptoms you have. Mine is the outer side of my thigh. I slowly run my fingers down from my hip towards the floor until I find the trigger point. You'll know when you find it. Take a baseball, tennis ball, or a couple fingers and start rubbing that spot. Yep it will hurt. Do it for 10-15 minutes and then ice for 20 minutes. Do it three times a day for a couple days and it will start to feel better. Other than that stretch. Google hip stretches and you'll see plenty to choose from.
I have had significant issues with the IT bands, especially as I lose weight and with the weight on my hips and knees changing. I do nighly stretching of my calves, hamstrings, glutes and groin muscles before bed. It has made a big difference.

I am firmly convinced that stretching is a major factor in maintainting mobility, muscle strength and overall health as I age.

We were always pushing the limits of what our muscles would do as kids, yet we reserve them as we grow older..and the price for that is pain. Stretch them as you work them and gain the lost youth back.

Just my opinion...and it works for me.