When i walk fast or jog i get major side stitches within seconds which hurts my performance in gym class. also worried it may be appendix?

The "stiches": are usually do to BOWEL GAS collecting in the upper curves from the "shaking" and can be reduced by limiting the gas producing foods such as beans/carbonated beverages) and taking an OTC anti GAS medication (eg" GAS-X") (containing SIMETHICONE!!) BTW Appendix pain is NOIT RECURRENT once it happens the appendix will GET WORSE when you stop the exercise! Hope this helps! Dr Z