Hello and welcome to the frog forum!
Your frog may be staying there because the rest of the tank is too cold. Daytime temps for pacs should be 80-83 with a drop at night to 75-77 (sorry fahrenheit).
Are you dechlorinating the water? If not, you should be. Seachem prime is a good one.
When the frog buries, he often poops in the burrow, when he leaves his burrow, check for poop.
I will also post a care sheet
http://www.frogforum.net/content/pac...-breeding-170/