Dr. Robert Scaer says yes.
Dr. Scaer is a neurologist so he looks at physical health from the perspective of the brain. This might seem to you like a big leap—that the way our brain reacts could affect our body, but stick with me. Dr. Scaer makes a very convincing argument for his point of view.
If you want to read exactly what he says, get a copy of his book, The Trauma Spectrum. Here's my nutshell version...
When you have had distressing or threatening experiences in your life and you weren't able to stop them happening, you've stored these traumas in your brain and body. Now when something stresses you—even if it's minor—your brain thinks it's a replay of those earlier events. It goes, "Yikes! Emergency!" and sends your body into a big reaction.
That reaction is what triggers the symptoms of fibromyalgia and IBS.
So how do you stop it? Not by trying to correct all the physical symptoms one at a time. There are too many of them and they are not at the root of the problem. The root is your brain's over-reaction.
According to Dr. Scaer, IBS and fibromyalgia are both conditions that are triggered by trauma stored in the brain and body. Dr. Scaer thinks that once you calm this down and basically reprogram your brain to react differently, your symptoms of IBS and fibromyalgia should start to clear up automatically. So you need to work with a method that releases trauma from your system.
He suggests using mind-body therapies such as Somatic Experiencing (SE), Eye Movement Desensitization and Reprocessing (EMDR), Thought Field Therapy (TFT), the Emotional Freedom Techniques (EFT), and similar methods. The interesting thing about these methods is that once you use them to release the trauma, you can actually make permanent improvements to your health.
Dr. Scaer suggests that modern medicine doesn't have good ways to help resolve chronic health conditions like fibromyalgia and IBS because the brain and trauma connection has been studied by so few medical researchers.