Vinegar and Brown Paper

In the legend of Jack and Jill, we learn early in the account that Jack fell down and broke his crown. Thereupon, up Jack got and home did trot, where, he went to bed to mend his head in a way that always seemed odd to me (let alone the way Jack selfishly deserted Jill without a second thought), "with vinegar and brown paper."

Today, the brown paper seems less odd to me, having read in Dickens' Martin Chuzzelwit, that when Mr. Pecksniff fell, his daughters attended his bruised head with "patches of pickled brown paper." Ah, now history begins to come into focus. So this remedy, evidently, was all folks had in primitive times, before the BandAid.

I can remember my dad singing this to me at bedtime when I was but a wee tyke. I'm sure he meant to calm me and get me to sleep. But I just lay there worrying about Jill and wondering about brown paper.

Plus, why was Jack wearing a crown? Was he a young prince or something?