I don't know if you can find Ivermectin in Pakistan, but it is effective against chicken mites. If you have a store that sells medicine for farm animals, look for Ivermectin paste, used to treat horses, cows, and goats. You can also find Ivermectin pour-on, but in this country it's much more expensive than a tube of paste.
Anyway, either kind of Ivermectin can be used to get rid of mites. Rub a thin film of the paste or the pour-on on the chicken's feet. The pour-on can also be rubbed into the skin under the chicken's wings to kill roundworms, lice, and other parasites.