Help needed! Any advice on sleep routine??

Urgent advice needed! My 6 Month old baby used to sleep around 9.5 hours through the night since he was like 2 months old (from 8:15 pm to 5:45 ish), it was wonderful! But all of a sudden, starting this week, he began waking multiple times through the night, crying and needing to be held by me. I rock him and when I put him back in the crib, he wakes up again crying! He is not really hungry (tried feeding him) and the only thing that seems to work to sooth him, is mama’s arms. It has been exhausting because I have to be at work at 7:30 am and haven’t slept at all! We had an amazing sleep routine 😩 What can I do? Has anyone else gone through something similar? Any words of advice? Should I let him cry it out..? Is this just a phase?

Thank you!