Feeling nauseous whenever I try to finger myself

Whenever I masturbate, I always have to do it through clitoral stimulation. I enjoy it but i‘ve always been curious about fingering myself. But every time I try, I get nauseous immediately. and I mean IMMEDIATELY. Like the second I stick a finger in, my stomach starts feeling upset. I’ve never had sex before and I’m worried that I’ll never be able to. Like what if I can’t get over this? I don’t even know what’s wrong, or what’s making me feel like this. I just wanna know any possible reasons why this is happening, and how to help it. Thank you for reading. This is really embarrassing to talk about but I feel like I need an answer, or at least some help.