i am sorry to hear about your passing frog,
there is a post on here about stress, and first aid for frogs perhaps these could help? i do not know how to cut and paste or link yet but there are on the main sections of the forum.
as for a calsium supliment theres many dustings for the crickets you can apply routenly when feeding.
every time i feed my white's tree frogs and firebellied toads i dust them in a coating of Nutrobal, its around £5 a tub and you only need half a 2.5 ml spoon in a pot of crickets, once its placed into the box of crickets take it outside and shake the box gentaly to apply the powder, i do this as its a bugger to clean of the floors, and the dusting gets everywhere, then its feed as normal, this will also liven the crickets up ready for feeding.
its a calcium balancer and multivitim supplement. may be this will help with your remaining frogs, im no expert myself and i am new to the site my self, theres plenty of information on this site and find it fabulouse,

i hope this will help, reguards ladydeath