I Have Random Red Raised Welts On My Body That

I have random red raised welts on my body that are very itchy. I am not exposed to fleas or other biting insects, no change in diet or environment. The only changes in the last 2 months are starting farixga and Prevident 5000 1.1% fluoride toothpaste. Could the welts be an allergy or what? any suggestions on how to get better? I take Benadryl and use itching lotions. thanks