Is it permissible to travel to perform Umrah with the intention of seeking healing for a sick son, then return to pay off the bank loan that has not yet been fully repaid?

It is not permissible to borrow with usury for furnishing a home or for any other purpose, due to the severe prohibition stated regarding it. Whoever has borrowed with usury must repent to Allah and repay only the principal amount. As for the usurious increase, it is not obligatory for them to pay it. However, if you fear harm or accountability, then pay it, while disliking this reprehensible act.