Sub-page stole the main keyword - how to fix?

Hey there,

I have a blog on a medical topic. Now I have the problem, that one of my more detailed posts "ate" the keyword of the broader post. To clarify an example:

Keyword A (2000 searches/month) - "Liver": A post about all aspects of the liver, also a small passage about "When the liver hurts"

Keyword B (200 searches/month) - "Liver hurts": A post that digs deeper into reasons for liver aches etc.. The post links to broader post and vice versa.

Now after some months "Liver hurts" is 2nd place in the SERPs, great, but my "liver" post doesnt't even rank anymore - searching for "liver" only leads to the "liver hurts" article now, but only on place 40-something.

How do I fix this? Do I have to delete the "liver hurts" article? Integrate it into the "Liver" article? Any other possibilities, to get my "liver" article ranking again?

Thank you very much for your help!