There may be some herbal formulas that are helpful overall, but the best treatment would come from seeing a practitioner in your area and working on the underlying issues. As you are finding canker sores are generally from deeper issues in the body and treating those deeper issues is what Chinese Medicine does by it's very nature ( see "Treating the cause and not the symptoms").
Many times canker sores that relate hormonally will be from what we call liver qi stagnation - nothing to do with your liver (see "my liver is what?"). But there are a few other possible diagnoses in Chinese Medicine terms including heart fire and stomach and spleen damp heat among others.
I would suggest you see a practitioner locally and obtain a correct diagnosis, with that, if appropriate, you can choose the correct herbal formula(s) (see "how to choose an herbal formula").