My 5 week baby has a rash on his face. how do i know if it's just heat rash?

Type of bump/none: Heat rash is more a widening of pores with red accents but no raised bumps. Babies often get a transient "baby acne" that is not present at birth (bathed in the waters of the womb) but comes out at a few weeks & lasts a few months. It is thought to result from maternal hormone effect which gradually declines as the baby ages.It will generally disappear without specific treatment.

See a doctor!: Most rashes are benign, meaning nothing to worry about, but if there has been a preceding fever, it is important to know what kind of rash by visual inspection, by a Pediatrician or ER, or Family practice physician - some viruses are dangerous, especially in the late summer and fall, for newborns and children, so go see your doc ASAP !