MUST be a root cause in lifestyle related to food/ sleep/ work you do.
It seems digestive system origin back pain as per details you have given.
Next Steps
Need details to conform to prescribe a medicine.
Health Tips
Can fill warm castor oil to navel or umbilicus by laying supine position in empty stomach or before food twice a day
can help in 2 days by making bowel movement smooth.
if not better to consult to find the root cause