Thank you, everyone, for your input. Indeed, I have Rheumatoid Arthritis and, at first, the discomfort was a bit alarming, but it's leveled off and is dissipating, now. The Seasalt water flushes help a great deal and I also get my selenium from Brazil Nuts - a couple every day in the AM when I'm doing the massive supplementation.
BUT - this time around, it's quite manageable and I haven't had any thoracic discomfort/pain, yet. I'm not increasing my dosage until I feel I'm managing the roooomatizz and thyroid issues, first. Once I'm comfortable with those issues, I'll probably up the dosage - we'll see.
Again, thanks for all of the excellent input and links!!!