What happened to my sweet potatoes?

[Farmette]

I grew sweet potatoes last year quite successfully. This yr I grew several varieties in a new raised bed as well as the variety I grew last yr. Most of the potatoes are very long and thin, almost like carrots. There are several have much of the inside missing and in some cases just the skin is left. Along with the debris, there is an abundance of worms. From what I have read, my soil might have been too rich and that would explain the skinny tubers, but what about the hollowed out larger tubers? I've included pictures. Thanks!