Your phrase "Talk to an expert today — completely confidential consultation" is perfect for delivering an effective and trustworthy message. If you want, you can make it a little more professional or attractive, such as: Short and punchy:

Consult an expert today — 100% confidentiality guaranteed.

A slightly sympathetic tone: You are not alone — talk to an expert today, completely confidential and secure consultation.

Professional tone: Contact an expert today for a reliable solution — your information will be kept completely confidential.

Call to action (CTA) style: Don't delay — talk to an expert right away. Consultation is completely confidential.

If you are using this for a website, banner, health app, or clinic, I can give more suggestions depending on the context. Tell me where to use it?