Although I have always groomed my cat about 2x a week, she suddenly has knots.?

She hates the groomer and becomes very stressed. I have tried different combs, tangling solutions, baby oil and even cutting them out.i haven't seen her chewing them or anything different in her habits, I'm just lost. I tried to gently bath her in the sink but she is pretty old and set in her ways. Plus I look like I was attacked by a cactus. Got any ideas?