Hi, why. I'm Mitch. Welcome to the forum. I've read your posts, and the other members replies, and here is how I see things.
First off, it seems to me that your boyfriend is very lucky to have you. If you have allowed him to continue tickling you, after the incident where you became physically ill from it, you are truly being extremely selfless, and sacrificing your own needs for his. This is a very admirable quality, and any guy would be lucky to have that. That being said.
I never like to get on my soapbox, and preach to people what they should do. I will thus post this from an "I" position. If I wasnt into the tickling interest and fetish, and I hated it as much as you do, and my girlfriend or wife tickled me to where I became physically ill, I would have to have a serious talk with that person. I would tell them that I loved them, and wanted to accomadate them, but that they were going to have to compromise with me. I would tell them that I would give the tickling my best shot, but that they were going to have to modify their techniques. I had suggested to another person on here to perhaps set an egg timer or stopwatch, for a reasonable amount of time that you think you can endure tickling, be it 30 seconds, one minute, or whatever. When the stopwatch goes off, if you dont feel ill, or physically overcome, rest for a bit, and then set the stopwatch again. This way, the tickling takes place for very brief periods, your boyfriend gets his tickling in, but it isnt unending torture for you. This is an option I can think of for compromise.
Good Luck. I hope you can find resolution with your boyfriend over this issue, and I hope what I said would be of some help.
Mitch