Why can’t I insert a tampon and should I see a gynecologist about it?

I’ve never been able to insert a tampon. It’s not necessarily painful, but the thought of putting something finger length inside me makes me feel incredibly uncomfortable and almost nauseous. When I tried once, I couldn’t get past that feeling and had to stop. I’m wondering if this could be something physical, like my anatomy or muscles, or if it’s more of a mental block. I don’t have pain otherwise, but penetration makes my body feel tense and uneasy. Has anyone else dealt with this? What helped you, and would you recommend talking to a doctor?