It sounds as if you have a muscular imbalance in your lower back or are tilting your pelvis to one side. Either could compress a nerve and explain your discomfort.
Have you tried any back mobility exercises? If not, spend a minute each doing the following:
- 'The Superman', where, starting on hands and knees you extend your right arm and left leg and then bring elbow and knee together before extending again. One minute on each side.
- The 'Jane Fonda swivel', where you twist the upper body to look behind you, keeping the feet planted.
- The yoga 'upwards dog' and 'downwards dog', where you alternate raising your chest from the floor with your arms while lying on your front with forming an inverted 'V' with your bottom highest.
- The 'lunge stretch', where you take a large step forward, bend the forward leg to 90 degrees and, placing your hands on the knee in front of you, push up to extend the upper body. This one helps stretch the tendons and open the pelvis.
Only do these for so long as they are comfortable.
The exercises and stretching are the hard work and need to be done 3 times a week but what I've outlined will only take 5 minutes.
For more immediate benefit, please consider applying some Anica Gel (Atrogel®) 2-3 times a day and 300-400mg magnesium daily.
Hope this helps over the next few days and weeks