Why I hate the index finger (1980)

I could relate to the claims in the article: for the last 6 months I've had soreness and pain in my left index fingertip that has confounded the doctors I've seen about it, and all that's helped is to avoid using it. Perhaps someone here has experienced something similar?

When typing I feel pain initially at the fingertip where nail meets skin, which worsens and radiates around to the middle finger side of the fingernail after more use. Even when typing without using the index finger, stretching the finger to keep it away from the keyboard induces some pain after a while. If I cut the nail very short, I think I notice some tenderness and loss of sensation in a spot near the middle of the skin just under the nail edge.

I think the pain developed over time while heavily using a split mechanical keyboard (kinesis freestyle edge) with poor typing technique and putting repeated pressure on the tip and side of the finger, but it has not gone away after switching to something more comfortable (kinesis 360). I don't remember any significant injury happening.

The only visual sign is that the skin seems strongly attached to the nail near its edge, there is minimal free edge compared to what my other fingernails (which are all short) have. Actually that is somewhat true of the other index finger, but to a much lesser extent. There is nothing apparently abnormal about the skin under the nail but perhaps any issue isn't visible.

Interestingly, the pain seems worse when my hands are warmer.

X-rays/MRI/ultrasound scans showed nothing abnormal apparently. All my internet searching for an explanation has yielded nothing, hence writing this comment to see if anyone can help.