welcome to hcm
thanks for the query
it may be due to physical exercise i.e musculoskeletal pain
. are you getting pain after playing sports?
if you are getting it in other times also then you have to consult your doctor for investigations of cardiovascular system,respiratory system or gastrointestinal problems. do you have any problems like asthma
,acidity.but all these causes are rare.the most common cause is idiopathic i.e no cause. generally in your age there is rapid growth of body. so there is frequent pain in this age group
but my advice is first to rule out the possible causes by consulting your doctor.
if you have constipation
problem then drink lot of water. have lot of fruits, green leafy vegetable(fibres)..you can also take some laxatives in night under the consultation of doctor