idk if clogged ducts is the same as or similar to mastitis, but when i had mastitis i constantly massaged my boobs between warm compresses and i felt like that was my quickest relief.

Are your bras too tight? Underwire? Sleeping on your belly? Also, when you pump if you can figure out a way for your boobs to hang more, so gravity helps. when I had a clogged duct I fed my son on his changing table and massaged the hell out of the bottom part of my boob. That seemed to loosen it. I am sure he was wondering what the heck we were doing.

I massage whole pumping sometimes I get a whole oz extra from doing this! @kirt

try hand expressing in a hot shower