Molars?

How long does the coming in of the first set of molars last? We are on week 3 of misery. They have cut already, but probably still coming through. Our son is waking up crying 2 times a night on average and he holds his jaw poor thing. Also irritable as hell during the day. I have my remedies, they just don’t work at night very well. I know it’s not a sleep problem because when he wakes up immediately crying (his pain cry at that), it means something serious for him. If it’s been him fighting sleep or a developmental thing, he whines. This all started with the damn molars. Anyway, how long does this hell last?