Sounds like you are finding good partners for your business! Those are all great pools of potential customers. 

Are you letting these other businesses market your product with their label? I could see a podiatrist having "Kellog Podiatry Foot Cream" they recommend for their patients. It is a relatively captive audience and benefits you and the business. It might violate professional ethics for medical offices to promote something like that, but I could see running stores or footwear stores liking that extra bit of branding. 

Also, have you thought about reaching out to diabetic associations or coaches who work with diabetics? Feet are an important area of personal care for those with diabetes, and could be another very good market.