Can't strecht hamstrings, get only shin/knee pain

Hey everyone, I have a weird problem and hope someone had the same issues.

When I bend forward I never get to the point where I feel my hamstrings stretching. Instead I get pain in the front, like at my shins and around the knee area. I can provoke this really well when I sit high up with my legs hanging loose. Then I make a strong round back, head down. When I extend one leg in that position it starts burning/pulling very soon at the shins/lower knee. I can make it worse by pulling my foot towards me (so dorsiflexion I think?). And I can make it better by moving my head backwards while staying in that rounded position.

So the pain goes away a bit when I move my head back, and gets worse when I pull the foot up. I already went to an orthopedist and physio twice and they also said its nerve related. Claude says the same thing. The physio gave me exercises to improve on that, but what I'm actually looking for is people who had the exact same symptoms and which exercises helped YOU. Also I am very curious whether it has gone away completely so you indeed could bend forward to stretch the hamstrings (which is completely impossible for me currently).

Thank you so much for any advice… I really need to get this fixed. It handicaps my quit a bit in my daily life…