I know that you said that you have tried probiotics, but have you tried homemade cultured vegetables or other fermented foods? It may be that your digestive system was somewhat disrupted by the change of diet (even though it was a good change). I found that by adding fermented foods to my diet, it made a huge difference.
Try making your own yogurt or cultured vegetables. If you make them yourself with a "starter" there will be many more probiotics in them that the grocery store products. That means the probiotic action will be much more effective.
Here is a link to provide you more information on fermented foods. There is also a link at the bottom with more information on how to make your own fermented foods. http://www.antiaginganswers.net/fermented_foods.html