Tips on transitioning baby to crib

My son is 13 weeks today and when we saw our doctor two weeks ago she recommended we start putting him in his crib to sleep instead of the bassinet. Well needless to say it’s been a difficult transition!

He used to sleep through the night but ever since he has been in his crib he wakes up after only 3 hours and then will not go back to bed! Last night he slept from 10pm to 1am and then he woke up and would not go back to sleep until 6am! We tried everything, including caving and putting him back in the bassinet but he would not sleep. His sleeping has been terrible ever since we started with the crib. I’m just wondering how this transition went for other moms and if you have any advice or tips to help baby sleep better at night!

Thanks in advance!!