Hip pain, instability, and inability to bear weight?

Hey there! I'm 23 years old and I've got this on-going problem. I've got this hip pain that began when I was perhaps 19 years old. It happened so infrequently that I didn't worry about it. Seems to be brought on by heavy lifting and the like. (I was working as a CNA in a nursing home at the time, so getting residents up and down was sometimes a very strenuous job!) In any case, it just happened very infrequently and I would get off of it and rest and I'd be fit for another day. I'm now pregnant with my first child, and weigh maybe 140 pounds, more than I've ever weighed in my life, and for the past few weeks, this hip pain has been nearly a daily thing. Painful, to the point where walking up the stairs is nearly impossible, and shifting positions in bed is difficult. I don't know how to describe the pain, it's not dull or achy, nor is it stabbing kind of pain, maybe more of a pinching pain, only in the joint, and lasting as long as I'm bearing weight. Even lifting up my leg is getting to be difficult now, like if I'm laying in bed and I just want to raise my leg, it's getting to be painful. Anyhow, I'm wondering if anyone's experienced anything like this, and what it ended up being. I've done the WebMD symptom checker, and I can't find anything that seems like what I'm having. I do have other joint problems, but nothing that's brought on by activity as this seems to be. I'll be asking at my next OB appointment about it, but in the meantime I'm very curious. Any help will be greatly appreciated!