Chickenpox incubation period longer than 21 days?

[Shortybabe7]

Hi. Has anyone know chickenpox develop later than 21 days after definite exposure. My son is 23 days post exposure and has some spots but none are anything like what is usual for chickenpox.

where are the spots and what do they look like? He could also have been exposed to someone else with chicken pox after the initial exposure that you know about

They're mainly on his lower trunk (front and back), up his sides, armpits and two on his temple. With a few randomly spotted about elsewhere. Some are like acne spots with no head and some are like red pinpricks. Trying to figure out how to add photo.