Hi, I have found with a low back problem, the pain can get worse with standing, bending, lifting, or laying on my stomache. I only have trouble with constipation when my low back is acting up. As for urinating or problems there, I will get bladder pressure also when my low back is bad, but no burning pain, and I have to go way more often. My pain is a bad ache and pressure. It will also go into my hip, and sometimes my leg. Have you had x-rays done? With your symptoms, I would guess they should do more blood tests to rule out bladder or kidney infection, and do x-rays, if nothing is found, then an MRI with contrast. This will show any disk problem and if any nerves are pinched. I get my injection today so I will be off here untill tomorrow. good luck and I will be back when I can.