I too suffered a stress fracture of the tibia. This took nearly six months for the pain to ease to the point where I could cross train on it, and 9 months before I could run on it.
Having seen several physios and a couple of podiatrists, my advice is those nodules need to be massaged to break them down, as otherwise they continue to rub against the muscles and tendons and delay recovery, and can cause inflamation and dull pain.
My physio showed me how to do this by massaging quite deep along the bone with my thumb, and told me that it was important that I did this to aid recovery. I have to warn you that this initially can be quite painfull and will leave you sore for a couple of days, but really does help in the long run. I would ask your physio about this and they should be able to show you what to do.
Btw, if you do massage deeply I wouldn't advise running for a couple of days as it will initially inflame the leg slightly, but cycling and swimming are great substitutes to keep the fitness up.
Dot, I suffered hugely with pretty much all knee problems between the ages of 12-15. This was mainly put down at the time to doing triple jump. Saw Chiro (can't remember why but had been recommended) but not physio. Was also playing a lot of football at the time. This injury reoccured in various different forms, both at the knees, and also in the shins. In fact it is only really within the last year of seeing a new physio and podiatrist that this has been solved.