Hi Deidra,
Is there any pain involved? If so, then a formula known as Tong Xie Yao Fang might help. It treats Liver Spleen disharmony that manifests as spasm, which in turn can manifest as abdominal distension and cramping pain.
Does the gas have any odor? If so, then it's less likely to be due to Qi stagnation and spasm, and more likely to be due to Damp accumulation. If the pulse got weaker in response to Si Miao San, then you might need a tonifying anti-Damp formula, like Wei Ling Tang. San Ren Tang is also a possibility, but is more cooling and less tonifying.
I'm pretty sure one of those will work. Chamomile and Wild Yam, like Wei Ling Tang, is a good peristalsis regulator, but doesn't address any Damp. It's quite powerful, though, at relieving bloat and pain, and works well in a case that responds to Tong Xie Yao Fang. In other words, it provides rapid relief in the short term, but is not as curative as Chinese herbal formulas in the long term.
Hope that helps in some way,
Steve