You certainly can boost your immune system, but it´s not an overnight thing, it takes time, months if not years. Some cultures (I´m thinking of Russia, where I spent some time, but others also) believe that all well-being all comes from the gut. If your gut works well all else will follow. You have to eat (reasonably) healthy food all the time, plenty of fruit and vegetables, cut down on wheat and sugar, leave out all the convenience foodstuffs. The Russians are great believers in drinking kefir and eating fermented vegetables (kimchi). Also lots of garlic. All medicines, over-the-counter pain relief tablets and antibiotics play havoc with your immune system. Plenty of exercise and a positive outlook add to a sense of well-being. Hope you feel better soon.