I have a dull pain in my left waist when I sit, not very painful but very uncomfortable. It's okay to lie down ... what's going on?

According to your situation, you need to consider the possibility of lumbar muscle strain, which means pain on one or both sides or in the middle of the waist.

Guiding opinions:

You can consider going to the orthopedic department of the hospital for a CT scan. If diagnosed, you can take diet therapy, kelp, litchi and fennel. Decoct with water once a day. Western medicine can be used: analgesic and antispasmodic drugs, fenbid, aspirin and indomethacin. It can be used when the pain is severe, but it is not suitable for long-term use. You can stand with your feet shoulder-width apart and your hands akimbo to prepare for the posture. Then do full waist flexion and extension four times, and try to relax the waist muscles during exercise.