I have a 6 months old MM Petrucci, and recently I've found that the neck has gone in pretty serious backbow, I didn't notice it untill action on a guitar changed very drasticaly, it buzzes on first 5 frets (not a big problem) , till the 12. fret is low buzz-free, and after 14. fret to the 24. is almost unplayably high. Truss rod adjustment didn't work, is there anything I can do? I bought guitar secondhand , so I can't send it back for a repair. Thanks!