I’m so sorry for your loss, I can’t even begin to understand how you feel but I’ve lost one of my oldest brothers and it was really hard for me and my stutter when that happened. My stutter just ended up getting better eventually, but you might try therapy (which I’m sure you’ve already thought of). It also could be a subconscious trauma response that your body is doing. But I wish I had an answer, and once again I’m sorry for your loss.