How can I get my baby to stay asleep?

Why won’t my 4 month old sleep, he no joke wakes up every hour just for me to breastfeed him for .2 seconds until he falls back to sleep. I’m EXHAUSTED, I’ve been up with him since 12:30 and my toddler just came in my room and won’t go back to sleep so now I’m up for the day. I got 2.5 hours of sleep last night. Someone please give me tips on how to get my baby to sleep, even his naps are like 20 minutes.