Okay, it is interesting you ask this. I have horrible fireblight this year on my pear trees which aren’t too far from the raspberries. I noticed just yesterday a drooping browning raspberry cane -that had been brand new growth- and it reminded me of fireblight.
In my head I said, “Huh, that looks like fireblight, but raspberries don’t get fireblight- maybe it’s cane borers?” Then I had to go to work and haven’t though of it again until I saw your post.
Please let me know if you diagnose yours.