You mentioned you "tried high dose c." The important question is: How much and for how long?
If you are interested, you may care to consider this: Dosage is the key! As an example, if a doctor prescribed a dose of antibiotic to a patient, it would come with both an amount and frequency of dosage. Hypothetically, if that patient decided to cut that prescribed antibiotic dosage in half, and/or ingest it at one-half the prescribed frequency, and then did not get the results expected, could we really/honestly say that they tried the antibiotic out, and it did not work? And so it is with ascorbic acid. Dr. Robert Cathcart, M.D., wrote that he did not see significant results in his patients until they approached Bowel Tolerance: "The clinical symptoms of...diseases and other conditions...are markedly ameliorated only as bowel tolerance dose levels (the amount that almost, but not quite, causes diarrhea) are approached."
And this similarly from Dr. Thomas E. Levy, M.D.: "The three most important considerations in effective vitamin C therapy are 'Dose, Dose, and Dose.' If you don't take enough, you won't get the desired effects. Period!...you will rarely ever fail to observe a dramatic response...IF you take a large enough dose for a long enough time."