Hi Kim,
I get the same thing. It's always good to see a chiropractor because they are the back experts.
Ibuprofen doesn't mask pain. Ibuprofen is an anti-inflammatory. When moving and taking a hot shower you are getting blood to the area allowing the cartilage to get blood moving into the area. The effectiveness of the anti-inflammatory may be due to the movement of fluid filled with pro-inflammatory chemicals being pulled out of the area and exchanged by fluid filled with anti-inflammatory chemicals.
The cause could be any fold. It could be due to a muscular imbalance. That's my main cause. My leg muscles are so strong they pull on my hip muscles and the hip muscles pull on my lower back. My lower back is where the pain is but the cause is tightness in my quadriceps muscles.
Have you ever been to a massage therapist? Have you ever used a foam roller? The foam roller is a $25 alternative to a massage therapist and or chiropractor but not a substitute.
Hip & Lower Back SMR Mini-Clinic
http://www.youtube.com/watch?v=8X6f6sPBBOg