Hello and welcome to the forum and I'm not an expert but I think it looks like shell rot. I may be wrong some one will see your post and answer your question. If I have a question and no one gets back to me the same day I write something else on my post so some one can see it again
It took me a while to get the stuff I needed and the right info well close to the right info. I still have some more things I have to do. Here goes nothing!!!!
Sorry for your lost... I hope you guys can find a better healthy one soon it hurts to hear these stories. But they are lessons to be learned. Oh and hello and welcome to the forum