When you massage them it helped them relax but because you have a tight achilles tendon it is pulling harder on them because they were freed up. As the tendon is more than likely tightened up you have to free that up to get the pressure off the muscle and here's how to do that:
Achilles tendon:
While sitting and your leg on your lap, take both thumbs and place them side by side at about ankle height on the tendon on the back of your leg and apply pressure hard and hold. After 30 seconds slowly raise your toes up as far as you can, release the pressure but hold your foot there for another 30 seconds.
For best results relax your body first by taking a deep breath and exhaling then remain this relaxed.