My 1 month old son has developed rashes in form of small red bumps all over his body including face neck chest and back. What should I do?

Baby acne? It's likely to be baby acne at his age, assuming that he is otherwise well and feeding normally. Baby acne tends to occur right around this age and looks like red bumps that get redder and stand out more when baby is upset or just after a bath. This goes away on its own in a few weeks. It is caused by maternal hormones that crossed through the placenta. No treatment is needed. .
Infant rash. Most of the time, this type of rash is a reaction to the soap or wash you are using on him. Switch to Dove sensitive skin soap only, most likely the rash will disappear.