Thank you so much acchabaccha.
Now I’ve got crutches for my son. I really appreciate your kind message.
I went to the Villagio Mall and I found one at Kulud Pharmacy. They did have one ... but not a pair. They called their branch to check stock for us and found out that their another branch next to the petrol station had one, too.
My son is now very happy to move around with his new crutches. Thanks again for your great help!