It's hard to eat so much it's bad for you, assuming you're getting a range and fibre etc as well.
However,it can be the order that you eat them in. As fruit is generally quite readily digested, so should be eaten before things that takes longer to digest. This way they are not trapped behind the other food.
Also, a sudden change to your diet can cause you to feel a bit ill, but assuming it's healthy and you're drinking plenty of water it should settle down soon and you'll feel much better.
Also make sure you chew your food properly (I'm constantly nagging my Mum for this, she doesn't and then complains when she feels ill!) and sit upright so your food can actually go down and any gases from digestion don't get stuck. Obviously your food will more down naturally due to peristalsis, but sitting hunched over can cause problems (this happened to me the other day when I was eating out and had to lean forward to reach the table, I felt awful!).
If you're feeling bad, try moving around, massaging your tummy, maybe having a warm bath. Make sure you are properly hydrated.
Hope you feel better soon