Jim beat me to it.
I had a bike fit from York Cycleworks last year.
Was getting really bad knee pain. Turning the cranks was a struggle
and 10mph was about all I could manage.
Went to see Sam, was booked in for a 2-3 hour session. Took measurements, tested flexibility etc. Then did the bike fit, cleat set up. Ended up with some new parts.
Went for a ride and the knee ache was gone. Just got in from a 30 mile ride and knees were fine. So money well spent imho.