All say it could be tonsil stone/ food particles traping in tonsil so yellowish exudate comes from it.i wana know so why my right jaw lymph node swell?

Tonsil stones: These are common and if they bother you, you shouldn't have to tolerate it. If you're resourceful, you can remove these yourself with a mirror, penlight, and half-unbent paper clip, or your physician can remove them easily. An ENT can perhaps laser-resurface your tonsils -- ask. Almost every young adult has at least one palpable lymph node in the head-and-neck region, often along the jawline.