Hello~It may be your appendix. It can cause intermittent pain, but as it progresses and gets worse, the pain can be with you all the time. I would certainly see your doctor and discuss this with him, he/she will probably order some blood tests and also feel your tummy around the area that is painful. I would suggest seeing the doctor as soon as possible so as to stop anything thing that might be happening from getting worse.
Right-sided abdominal pain may be caused by problems with your liver, gallbladder, biliary tree, right kidney, or right-sided bowel (ascending colon/cecum, appendix, and/or terminal ileum), or alternatively hernias.
Recommend clinical and/or laboratory correlation. If symptoms persist, consider CT abdomen/pelvis.