I would agree with hydration. this is massive to ensure the fascia is allowed to mobilise. Drinking at least two litres of water a day is boring advice but it works. All forms of alternative therapy share a common instruction: drink 2+ litres of water after treatment.
It sounds like you have a serious issue around your pelvis.
I do not like trying to assess over the internet as it is impossible however:
If it comes on after 45 minutes then this can be a weakness somewhere else in body, I am guessing your gluteal muscles which will cause your ITB and outside quad muscle to overwork which eventually you cannot tolerate the load any more resulting in pain on outside of your knee.
I would reccomend soft tissue work to ITB / Vastus Lateralis, glute muscles/piriformis, popliteus (small muscle behind the knee) and Iliacus and Psoas muscles. Bring this list to your soft tissue guy.
Then get your glutes and hamstrings as strong as humanly possible.This exercise will help and you should be getting upto 3 sets of 6 reps each side. I would avoid doing any quadricep strength work if you have been giving any as these will probably be overactive.