Canarygirl1, that sounds worrying. I tried a low calorie diet once and although I didn't vomit I just felt more and more ill with every day that passed, by day 10, I was too ill to go to work, so I had a couple of slices of toast, went to work feeling better and by the time I had eaten my lunch time sandwich I was as right as rain.
I tried again with similar effect, I gave up on day 4. I came to the conclusion that a low cal diet did not suit me. Tried the 5:2 diet when it came out and it worked like a dream.
It could be that the low cal diet is unsuitable for your.
DH is currently doing LC and suits him to a T - and he is loosing weight.