Is foamy saliva and a metallic/peroxide taste in my mouth a cause for concern? No blood. But when I notice it, I also feel hot/anxious.

Metallic taste. Could be related to your gerd or medications, but worth mentioning to your doctor.
See DDS-MD. Anything that does not feel or seem normal should be investigated. You should check this out with your dentist and physician, who after examining you and getting a complete dental and medical history may be able to answer your question.