This. Find a good massage therapist. Watch her work closely and ask for some techniques that you can do daily. One of my mares had a back injury at 5. I found that doing about 30 minutes of massage daily made a huge difference in between appointments.
Also, get a copy of Beating Muscle Injuries for Horses by Jack Meagher. It’s available on Amazon. Along with understandable explanations of different massage techniques, it has detailed drawings of the musculature and where the pressure points are for each muscle group. It describes the symptoms that you see for injuries to the various muscle groups to help you pinpoint exactly where your horse is sore when they aren’t quite right. It also lists various rehab techniques (hand walk, hill work, etc) for each injury location.
I kept my copy of this book (spiral bound, so stays open while you’re working on the horse) at my barns for decades and used it very often. It’s definitely a book that every horseowner should have in their library.