Work on stretching the vowels of words. I know its difficult but get that practice even on a discord chat it can be great practicing there. Cuz i also used to have sore chest, stomach and throat from the blocking but i sorta fixed that with dr mort cooper approach its basically where you hum your words feeling the vibration in your nose. Watch one of his videos or read his books. My theory is we have sore muscles there cuz we speak from thr lower throat muscles