Here your main question is on lower back pain but while giving the symptom explanation you have told a lot about your gastric problem rather then lower back pain. As per my suggestion this both may or may not be related. Let s take a look on your gastric issue: You have symptoms like after food frequent motion, and after that pain in stomach, as well you Don t feel to eat any thing. This all symptoms are indicating towards inflammatory bowel syndrome as well gastric ulcer. To get conformation you need to visit gastro-entrologist and need to have check properly. You may need to go for endoscopy too. And the report will let you know your problem. As per that discuss with your doctor for possible treatment and early relief. Now let s take a look on back pain: this can be due to back muscle weakness or loss of spinal curve as well spinal disc related issue. I suggest to treat your major problem first that is gastric problem and then if back pain is still not gone then visit a orthopedic take a x ray or MRI and based on report take proper suggestion. Here with minor problem doctor will suggest conservative management like physiotherapy and medication. And for any major issue doctor may suggest for surgical correction. In both the cases my suggestion is follow spinal exercises to improve strength and stamina of your spin. You can also use hot pack in your painful area to have some more relaxing and pain relieving effect on soft tissue. I also want to suggest one more thing correct your life style, food habit, posture of work, Don t take much of tea and coffee as well never take it as only tea or coffee always have some thing along with that to improve your gastric health further. Take care.