Once you get it fixed, if you son does sweat a lot, the aid should be put in a hearing aid drier each night to help extend their life. Also, there are protective covers that can be used while wearing then to reduce moisture damage. One site that sell these is Gear For Ears https://www.gearforears.com/. This is US based. Not sure if you can access it from Pakistan but if not search for hearing aid protection to see if someone in your area sells them ( they are like little socks that slip over the aid).