Oh gosh the diet change will definitely make you ill as a hornet. If you're doing everything right then I'd keep what you've been told up. I guess the sugar levels going nuts directly coorelates to the diet. Take it easy though, if you continue to throw up and your doctor just gives you the same advice it might be time for a second opinion. Last thing you want to do is mess yourself up when you're trying to get healthier.
When you do get the money for more vegetables/fruits, see if you can make veggie smoothies with them. I'm sure there are some recipes that don't suck around the Internet. Might make things more tasty.
By just parking farther back you're already making a big difference. Wait a bit before you take it any farther though, this is a huge change for your body. Last thing you wanna do is over exert yourself while it's getting used to it.
Also if you're watching nutrional values and calories, try out recording your food intake on
(you need an account to see links)
The app was god send for me.