Hi and welcome to HCM
IT MOSTLY APPEARS DUE TO MUSCULAR STIFFNESS
AND ACIDITY. DONOT WORRY A SIMPLE MUSCLE RELAXANT
WITH GOOD ANTACID
SHOULD CURE THE PROBLEM.
SUDDEN CONTRACTION OF MUSCLES OF RIB DUE TO PROLONGED POSTURAL ABNORMALITY MIGHT BE A CAUSE.
HOWEVER CHEST X-RAY A.P VIEW IS SUGGESTED.
I do hope that you have found something helpful and informative and I will be glad to answer any further query.