Changing my current permalink

I currently have a running website with the URL elitetherapeutics.com/products and I would like to change it to elitetherapeutics.com/clinical-products/…..Once I’ve made the change I can click on the products page and it will show all the current products I offer, however, when I click on a specific product it says the page doesn’t exist. I’ve looked at the URL and it’s the same for both versions just with the new url having “clinical-” added.

I had a company set this up initially so I’m not exactly sure what my next steps should be.

Thanks in advance