I'm used to sentences ending in a verb so I assume it could be translated as "Was watching the waves surge back". My mother's distant gaze." as separate phrases.
Am I right to say "My mother’s distant gaze was watching the waves surge back."
顔をしかめて 母が力なく言う 「痛いよ」
"The childish me grabbed strongly. My mother frowned and said without strength, 'It hurts'"
I think that's incorrect as I'm unsure of 'who's doing what'.