I need advice!

My son will be 4 months in a few days. He's was sleeping pretty well at night but now he's waking up every 2- half hour at night. we were able to put him down at bedtime and he would sleep 3-4 sometimes 6 hours now he's up within an hour and only wants to sleep in our arms.

He has is two bottom teeth and looks like his two top at coming in now. I don't know if it's his teeth bothering him or if this is the 4 month sleep regression.

Either way any advice? I'm really struggling with the lack of sleep especially with him fighting his naps now too. I feel like I can't catch up and my husband is about to leave for work for a month 😓

Help!