I'm very sorry to hear your news. I've been through OS three times with gh's that were in the 9-11 yr. old range. From first limp to needing to be PTS due to unmanageable pain was only 6 weeks with each of them. I did a biopsy on Derbs and would not do that again, due to the pain it caused. Repeat x-rays within a month will tell you all you need to know if it is OS. Any chance Dempsey was exposed to Valley Fever? It presents with symptoms very similar to OS, including on x-rays. A fungal test will rule it out. Please consider joining the Circle of Grey group. You have much to consider... age, location of problem, expense, chemo or not, etc. Once you have researched adequately and made your decision, do not second guess yourself. You know in your heart what is right for your boy. Sending lots of hugs and prayers for this difficult journey.