blowjob advice

so, one of my boyfriends ABSOLUTE favorite things is getting head. and I'm not always a big fan of giving it because he likes it when I swallow and to be completely honest swallowing makes me want to vomit so I hate doing it.... my problem is, his birthday is coming up, and I want to do something to totally blow his mind and make him super happy (sexually) and I know he'll really like this, so I wanted to know if any of you have ever been in the same boat and how you dealt with it? 

should I just be a trooper and swallow? or is there a way to make it easier for me? thanks!