Hey David I was just logging on to post a question about the same thing and I saw yours ha ha.

My Dad has that hard ball thing under his chin in the neck area. The surgeon and RO both said it's called a 'Dulap'.

They said it's from radiation. One dr suggested seeing a plastic surgeon. So he did yesterday. (The plastic surgeon use to work as H&N surgeon). He said it's like frying up bacon and all the grease that gets hard. He can fix it up by local freezing and doing some cuts and removing the hard stuff. He suggests waiting a few months to let things settle more.

Seems most people get this Dulap who had radiation in this area.

As for hair; my Dad's hair seemed to thin up to a few months after treatment finished and yes his too grew in black in certain areas; including facial hair (and he's silver grey).

Take care.