AKA mother’s wrist syndrome per Wikipedia.

From MayoClinic.com:

If you have de Quervain’s tenosynovitis, it will probably hurt every time you turn your wrist, grasp anything or make a fist…any activity that relies on repetitive hand or wrist movement — such as working in the garden, playing golf or racket sports or lifting your baby — can make it worse.

Note the tendons of the extensor pollicis brevis and abductor pollicis longus muscles, mnemonically known in anatomy class as the snuffbox.

So THIS is my problem!