What could this pain be?

For a few years now I have been suffering from lower back/hip pain. I have seen a few doctors over it and through X-rays of my back they say they see nothing.

I'm 29 years old and when I wake up I literally cannot get out of bed and immediately stand up. My back will not straighten that fast.

When my back hurts and I can't stand straight, I usually have to lay down and twist my back in an awkward way and its as if my tail bone pops back into place. It's loud and gross and if you r in a good distance u can actually hear it for yourself. When I get the actually pop, the relief I get almost brings a tear to my eye, it feels great. This is where I'm confused; I'm not sure if its my tail bone, hip or something else.

The last week or two it's been getting worse. And I notice when I'm laying down and I stretch my legs, in lift them to the air. my right hips makes like a popping sound that u can hear and feel. It's too the point that when I sit down for dinner, those 25 mins are torturous for me to get up and start cleaning.

I have three boys, who r very active in sports so I'm always running around & I work full time and I'm literally on my feet for an entire 8.5 hrs straight.

Doctors don't find anything wrong, I don't know what it could be or do at this point. I try icy hot and stuff like that but it doesn't work.

Any suggestions of what it could be?