theres a difference between constipated and impacted. too much food or calcium in relation to the water intake can contribute to either.
my recommendation;
1. reduce calcium
2. give extra water and dont feed til after it has drank.
3.gutload feeders with dried prunes, but feed chams at a reduced rate
4. not saying thats the case, but just for the record, not good to feed your chams all they will eat. and they should have frequent food/calcium free days. jmo