I do not have POA for my Mom who is incapacitated. I'm an only child and sole inheritor. She has a checking account with a US bank where pension payments are accumulating. She is an immigrant to the US and returned to Europe at retirement in 1990 to be with family and friends. I have her in a eldercare facility there where my cousins can look after her and am paying for 24/7 nursing care with my own funds. She is no longer capable of travel. The bills are high and without a POA I can't use her funds to help. The bank asked me to bring her to their office in a city which is a plane ride away - basically an undoable and ridiculous request - in order to have her request access for me.
While the bank won't give you access, they should be able to pay the Nursing Home directly from her account. Ask your local consulate to help with that.
cmagnum is likely right. Filing for guardianship may be your only route. You shouldn't be paying these bills yourself when your mom has the money. Talk with an elder care attorney for guidance. He or she may be able to suggest other routes for you to follow. If not, you'll have some legal guidance for filing for guardianship.
Please keep us posed on how you are doing,
Carol