You don't really need "AI" for this. For this "triage" use case a good expert system/decision tree is more than enough. Think of it like akinator for a given domain.
Hand-building the tree to be efficient is actually the hardest part.
Edit: yes, this is probably "AI" to some people, but AI only exists as long as we don't understand it. This kind of tech has been well-understood since the 70s.
There's a fair bit of AI, NLP, etc. The system starts out with decision trees built by/evaluated by medical professionals and learns what conversational elements are required to reach a diagnosis. This isn't just a trivial set of hand-built trees.
Hand-building the tree to be efficient is actually the hardest part.
Edit: yes, this is probably "AI" to some people, but AI only exists as long as we don't understand it. This kind of tech has been well-understood since the 70s.