How to cure 9yr old's glands and throat problems?

My son,whenever takes something cold and other stuff like lemon, grapes, sauce etc suffer frequently from glands and sore throat problem.he often doesn't eat properly and asks for sweet dishes made of sugar, etc.I want expertise views on what should I do to cure his throat problem and improper eating habits. Should we do X-ray, plz tell what procedure and medicine is best. If the problem continues, is he going into a big trouble, his voice shows cough problem in chest