hi i have an african grey and NALA is also 4yrs old.
she started plucking her feathers few weeks before,i am the member of the eelite parrot club and they told me to use (100% Aloe Vera juice) you can get it from walmart pharmacy.i used it on her in a spray bottle no water added it gave her a soothing effect and i did that for 3days and she stopped doing it now i spray it once a week.cause they have 75% dandruff in the feathers and it can give them lots of itch.my bird in 3 days ate all her neck and chest feathers but now no more.and if he swallows it no worry it is safe people drink it when they have intestinal problems.:woohoo:
good luck.
nasima.