This might sound silly, but since you woke up with an actual physical pain in your abodomen, could the dream have been about an actual physical problem. Tornado = wind = gas. Did the feeling of pain go away very quickly after you woke up? Or after you got up and walked around?

The weather in a dream can represent your emotions.

A storm, such as a tornado can be a sign of stress or pent up anger.The tornado can also represent something that is disrupting your life or is overwhelming you. You and your family trying to avoid the tornado can mean that you have been trying to avoid becoming too stressed out by something.

A house in a dream usually represents your self, your unconscious and conscious mind and all that theyare mind up of. So finding refuge in the house means that you are trying to find ways to cope mentally and emotionally with the situation.

The fact that you are engulfed by the tornado means that you can't completey avoid this difficult situation. Eventually, you are going to have to face it and deal with it.