It does sound like a strong dog responding to an unfair correction.
Some dogs will take whatever you give them, and some will not. I suggest getting into training with someone who truly knows strong working dog mentality, and change not so much your correction but your leadership style, so that there isn't any confusion.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC