My boys are the same. Its a boy thing to get more than one a day, I swear. Small bumps are just that. Lots of bigger ones (egg lump with bruising bumps) would be more worrisome.
With each bump though, what you need to pay attention to is how long it takes for him to cry. If there is an unnatural delay between bang and wah - then its best to get him checked out by a doctor. If its quick but the result is visible, keep him awake and alert for an hour.
Otherwise, you have a perfectly healthy and normal babe.
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