There was another recent question about leg pain, does this sound familiar to what you are experiencing: Right Leg Pain End of Day?
Do you exercise or are you physically active much during the day?
Are you on your feet, or sitting, most of the day?
What is your diet like?
You may try using a pillow between your knees when you sleep, to see if that helps. A heating pad may also help, if you'd like to stop taking pain medication this evening.
Also, make sure you are drinking enough water during the day; if is pain in a hip joint, that can help.
If you are not physically active, you may want to try exercise gently. Perhaps a pool would be a good choice? Soaking in a hot tub can help sore muscles (although you said it doesn't feel like a muscle ache).
If you are sitting most of the day, make sure your chair is comfortable, at a good distance from the floor (feet should be flat on the floor, or get a foot stool for under the desk), and good posture can help with your pelvic muscles.
Let us know if any of this helps!