Hi Movingo, I have exactly the same thing - ITB pain focusing on outside of knee. Marathon on 14th April. 6M ok before the pain hits. Be careful with foam rolling, I still think that triggered mine

but it could also have been hills, pace, longest runs I've ever covered... Who knows. I went straight to the physio when mine started after my 15M long run on 17th Feb. She used a metal instrument(?!) to gently massage where the ITB connects to the knee, and I've to carry on with that using a spoon. It does seem to ease it. Also, avoid hills - they hurt. And run off road as much as you can, I have found that helps massively. I can cycle and do pretty much everything in the gym, and I've been doing 2 spin classes a week to try to keep uo the fitness. It all helps. I can now run about 7 miles before it starts to really hurt, 6M pretty much pain free. I've entered a back-up Marathon in May, in case I cant get round Brighton... There is no point pushing it so hard that it makes the injury worse. There will alwasys be other marathons. Hope some of this helps, and Good luck with your training and your Marathon.