So, after the input of this forum, (and after spending some quality time at the local mouse counters), I ended up with a headache to go along with the pain in my arm and finger!
A lot of the ergonomic models felt very comfortable but, in the end, I chose the Logitech Performance MX. The buttons were very easy to actuate and, after reading endorsements from this forum and several reviews on Amazon, I decided to buy the one that seemed to have the most positive reviews.
On the other hand, I do like the way the Microsoft Scuplt felt in my hand. I didn't choose it because of how radically different it looked from all the others. But, truth be told, it felt the most comfortable to me. I didn't find the number of reviews I saw when investigating the Logitechs, though, and that made me wonder about it. However, at a price of $39. USD, I may end up buying one in the future and alternating between the two. Because the (3) button configuration of the Microsoft Sculpt is "typical", I believe it would be easy for me to alternate between them. Unlike my current situation...
When I started having this pain I told our IT guy about it and he ordered an Ergonomic Mouse from 3M. This is a "handshake" style mouse that looks more like a joystick. I'd only heard of this style of mouse and never saw one in stores, but I have to tell you, it solved the problem I was having with my pointer finger, - because there is no button for the pointer finger! Instead there is a R/LMB rocker that is actuated by the thumb and a button on the handle for the MMB. The "eye" is on the base so otherwise it functions as a "typical" mouse.
I like the fact that the "handshake" mouse has taken the strain off my pointer finger and repositions my arm. The problem is, with such a different button layout, I find it hard to get things done quickly without thinking about it. I've got both side by side at my desk and find alternating between the two is possible but not ideal. Further, I began getting a pain in my thumb! I may have used it too much at one time. Or maybe it's just time to bring the old horse out to pasture.
In any event, thank you all for your consideration and input. I look forward to participating in the future.
All the best,
condeg01