It turns out that the reason the tumor looked "inconsistent" was that there are actually two
problems with my arm - so close together that they appeared to be one. One is the lump itself, the other is a (and I'm trying to remember this correctly) tear where my bicep muscle attaches below the elbow. This tear is what looked like the little "tail" that had the doctors so concerned. It also accounts for the pop I felt which started this whole thing.
I can have surgery -- two surgeries -- one to remove the lump and one to repair the muscle, or no surgeries -- unless the lump grows or just offends my notion of beauty (it doesn't) there isn't any real reason to remove it and the muscle will eventually, probably, mend itself and won't hurt anymore. However, if I end up having to have the muscle repaired I will need to have the lump removed first.
There are pros and cons to both the surgery and the not surgery approach and since there isn't a hurry I'm going to wait a while. As long as I don't lose any muscle function or unless the tumor starts growing rapidly I think I'll just sit tight.
It was worth running all over town and melting a witch to get to this doctor. She was whip smart and absolutely hilarious, such a great combination when faced with having to see a spooky specialist.