Help!!

My 6 week old was sleeping 5-7 hours a night. The last two nights was only 2-3 hours, and now tonight he only slept for a half hour so far and woke up crying. He ate 4 oz of formula and I breastfed him before bed. He doesn't need a diaper change. I think he just wants to be held. He'll fall asleep fine in my arms. What's up with this? What do I do? I need to sleep!!