Playing through pain is not recommended. Poco a poco is better. Wrist pain in your strumming hand may be due to: 1. median nerve compression or traction, esp in the carpal tunnel if your hand is not relaxed, or 2. repetitive strain, if you use wrist deviation instead of forearm rotation. Regarding the chording hand joint arthritis, it would be helpful to know which of your joints are reporting symptoms, i.e. base of thumb or in the muscle spaces of the palm. Do you have swelling or nodules and whre is the location of those features?