Dear Sage, hello
Muscle pain can occur due to
muscle fatigue, occured as a result of extra work done by the muscles.
In your case, rigrous activity by your leg and buttock muscle along with low back muscles in your practice for juggling resulted in muscle fatigue.
Give some rest to your body and increase your training gradually. This will help the muscle to work without fatigue as your muscle will get trained gradually for more exercise.
Thanks.