See your doctor to rule out any medical issues. No it's not normal to be so "rearranged in there" that you have painful sex 3 years later. You should have a fulfilling sex life in much less time after delivery.
Once you rule out medical issues, you might benefit from chiropractic or more effective exercises and stretches to improve flexibility, muscle strength, etc.
The shooting pain down the leg sounds like sciatica - the sciatic nerve goes from your lower back and down each leg. It's more common in one leg than the other, often. Doing really good abdominal strengthening can help the back. So can better posture and alignment during the day. Mine got much much better when I joined a gym and did effective nutritional supplementation to improve muscle strength. There's also a fantastic new all-natural anti-inflammatory that is helping with so much health issues. I can give you info on that.