He may be more willing to accept your breast while he is sleepy, drowsy. So you may want to try to feed him while he is asleep, napping or just after he wakes up.
Some babies go on nursing strikes, it could be because of the taste of your milk or because of something else. I don't know it it is an old wife's tale but I have heard that if you eat chocolate ice cream or some chocolate your breast milk will have an appealing taste to your ds. Are you pumping while he is refusing the breast to keep your supply up? Even if he won't have it, do it just because of supply issues.
Yes, he may have a growth spurt, too bad he won't take your breast at that moment. Growth spurts are not always as it is written in a book, can happen later or earlier.
Check out this link, info on nursing strikes is at the bottom of the page:
http://www.kellymom.com/bf/concerns/baby/back-to-breast.html#linksstrike