Medicines and creams to relieve insect bites are available  for adults and children at supermarkets, chemists and local stores please follow the packet instructions. Consider using insect repellent such as creams as sprays to prevent bites in the future. The following information is taken from NHS Choices:

Most bites and stings are treated by:

• Washing the affected area with soap and water
• placing a cold compress (a flannel or cloth soaked in cold water) over the area to reduce swelling.

Try not to scratch the affected area to avoid infection and if you are in pain or the area is swollen, take painkillers, such as paracetamol or ibuprofen.