Type 1 problems with feet

Hi, my son is newly diagnosed type 1, and his feet/toes are covered in black lumps underneath. All I can say they look like are verrucas. And blisters too. Is this a common problem and how could I treat it all if possible without trying to get into see a doctor? Thank you for reading

I just wondered if it was a common thing as its all new to us as he has not been diagnosed that long ago. Will get an appointment at the doctors. Thanks for replying