newbie here w/ a question

[pinkandgrey]

Hello everyone. I'm on my 13th day of induction. I only need to lose about 15 lbs or so. I've been exercising regularly for about 2 years. I lost this 15 lbs about a year ago with a low calorie diet and gained it all back. I also have terrible sugar cravings so I thought I'd give atkins a try. I do feel great on this diet....my problem is though, every time I exercise now, afterwards I get really nauseous. Today I actually vomited. Anybody have any clues what this is about?? Thanks in advance