How long after you quit smoking should you feel the benefit?

I quit smoking two weeks ago (smoker for 17 yrs) and ever since I have woke up in the morning with a sore throat. I have also put on a lot of weight ( about a stone) despite eating healthy snacks (grapes, melon etc). I am starting to feel any health benefits I have gained from stopping have been undone by the extra weight I now carry. How long will it be before I actually feel any benefits from stopping ? Any ideas on how to boost my morale and feel good about quitting?