Ok so My A-string just started buzzing out of the blue and it buzzes open-11th fret. i lowered the action then raised it, adjusted the neck, adjusted the inotation, and nothing has worked. it still buzzes and its the only string that does. Help T_T
First, are the strings fresh or old?

'86 Carvin V220
'92 Carvin DC135c
'06 Fender Strat MIM w/Carvin AP11's
'08 Gibson Les Paul Studio
Epiphone LTD ED. SG w/EMG 81/85
Schecter Damien FR
'08 Ibanez Prestige RG2610E
'04 Carvin CT4M
'91 Jackson Professional Stealth Pro