I decided to go 85% raw vegan and I received IBS from it. Any suggestions or ideas why?

Food combining makes it worse. If I only eat fruit alone, or if I eat starches separated from proteins I get sharp pains in my stomach and excessive bloating. I stay away from processed foods. So I don't understand why I'm having digestion problems because I eat a substantial amount of fiber and no refined carbohydrates. I have tried digestive enzymes but that doesn't help either. I would love to hear any suggestions or ideas why this might be happening. Thank you for your time!