Julia, in the Waco area, the Spa at Canyon Oaks has a great reputation. No personal experience myself with it, sorry.
https://www.wacospa.com/ It is located out on Highway 6, west of town.
Cameron Park Zoo is fun, it is a lot of walking.
The answer in Killeen/Harker Heights is the EcoBlue Spa and Salon in Market Heights shopping center. They have a separate massage area with soundproof rooms, ambient lighting, feng shui settings, customize the sounds and aromas in each room, and great LMT therapists. Best legitimate massage and ambiance in the area.
http://www.ecobluspa.com/
Hope you get some relief soon!
Respectfully,
OldSarge