Struggling..

I had my 3rd baby 5 months ago and it is complete opposite of everything with my other 2. Hes in general a fussy baby but he does not sleep good.. like 2 months ago he was at least sleeping pretty decent at night but now hes still up every 3 hours to eat which is fine but then he wakes up when hes not hungry and screams and nothing i do helps him. Im over the mental break downs. Im over the no sleep. I dont know what to do anymore. Is something seriously wrong? Am i just too overwhelmed it making things worse? I dont know what to do anymore at this point..