Against advice, when my infant son gets small bumps I often jump up to hold and comfort him while he bursts into tears. Is it true that I shouldn't react with this behaviour?

How old is your son? If infant then definitely u need to hold and cuddle him. But for older children i would actually see if they can self soothe and 'suck it up'. When i tell my kid that its ok and not fuss over him too much I realise that he stops crying faster. Haha