Dear ,I have gone thru your query regarding pain under your left rib .
for your info pain anywhere in your body is a symptom of some forth coming problem . .and doing exercise is certainly not the cause of this pain if done properly ,rather it helps reducing number of problems.
It can be caused by
constipation and gas etc.
Gas itself is product of constipation .
To get relief frm this you can take a glass of hot water with a pinch of soda bicarb or salt with lemon juice and relax for immidiate relief.
Proper balanced diet including Minrals
Vitamins salts fat carbs protien and
antioxidants in proper proportion in natural forrm as Green. veges milk fruit .nuts ginger .garlic., and of course sufficient water preferable hot water . proper rest .and physical activity is must to keep your body health.
Avoid worry ,
anxiety. sleepless ness ,.
Regular check by your doctor is apriciable .
hope this helps to solve your query
pls don't hesitate to come back if you have any further query .
All the best .