I have small red bumps on my feet (80%), and some on my hands, belly, back or legs. They are itchy at first, then they hurt and then dry out.

Dermatologist. I recommend that you consult a dermatologist for diagnosis and treatment. This could be a problem of insect bites such as bed bugs,etc and it would be important to have a specialist diagnose the condition as soon as possible so that whatever treatment you need, even if it's not an insect problem, can be started without much delay.