Constipation Keeps Coming Back?

I've had constipation for a week, and after 99999 prunes and 1284425 bowls of all bran cereal, I finally went. I felt better for about an hour, but I got hungry and decided to eat some waffles. The constipation and cramps came right back, so I ate more prunes and cereal and about 8 hours of pain later, I finally used the bathroom again. Then I got hungry again and the same thing happens over and over. What should I do? I already used laxatives and an enema, neither worked.