What could be causing my chronic lower back and r leg pain that started after the birth of my little girl 2 .5 years ago? (sharp pain down r leg, numbness, tingling, discoloration, cramping)

Nerve impingement: can be caused by being sandwiched between two spinal bones, pressed by a bulging. It can cause muscle spasm and back pain. Prevention treatment is always recommended. See interventional pain management specialist for definitive diagnosis and management.

Multiple problems: Multiple different problems could be causing your symptoms. Nerve injuries within the pelvis or low back would be possibilities. Many of the pelvis/ low back structures are stretched during the birthing process and can refer pain down the leg. Additionally, the intra pelvic organs can refer down the leg. I would follow up with your ob-gyn to ensure no preg complications are present