Awe, that's terrible when they get so many pin-feathers at the same time...Sometimes a warm shower helps, sometimes you can actually help them if the pin-feathers are dry enough and ready to break-apart. You can very gently roll each separate pin-feather between your thumb and index finger and break them up for him...I actually find it sometimes easier to roll them between my index finger and the tip of my thumbnail, if your thumbnail is long enough to do so, it seems to be less painful for them.
The other thing that can help is some "Molt-Ease", which is made by Ecotrition and you can buy it in a good-size spray-bottle at any Petco or PetSmart. It contains both natural Aloe-Vera and Purcellin Oil, which is the same oil that they produce from their preen-glands and that they rub their beaks in and rub all over their feathers while they preen themselves...I've used it before and it really does stop their itching.