I have similar issues, from time to time. Sometimes worse than others. Everyone is different, and there's no substitute for a discussion with your doctor...that said, what helps me is Glucosamine, on a daily basis and compression gloves when even that can't keep the pain away.I looked up De Quervain tenosynovitis and I have the same symptoms. My doctor said it's arthritis, too. Don't know what the difference is.
My pain at the base of my thumb comes and goes. Left hand, but I'm a righty.
Lee
Lately, I've taken to using a "hand cruncher" device. An exercise thingy to strengthen my hands. I keep it handy and just use it several times a day. It has a progressive "weight" spring. I was so happy when I was able to give it a couple of twists for more resistance! Progress!