welcome to healthcare magic forum
pain on left side could have many reasons. but as you are telling it is occuring often could be due to left ureteric calculi. so do a USG of lower abdomen to find out the cause and consult to your family physician accordingly. drink plenty of water minimum 3to 4 liters and take more natural foods stuff riched with soluble fibers so if it would have been from constipation
problem can be corrected.