Help. Fussy baby

My baby is 20 weeks and is SO fussy lately. Nothing at all makes him happy. All night he cries... all day he cries... I nurse him, rock him, change him, play with him.. and all he does is cry.. what is wrong with him? I worry I’m not making milk, but I also know that is often an incorrect assumption.. I am just losing my mind listening to a baby cry nonstop and not being able to do anything to soothe him 😩😩😩 also my husband works the opposite shift that I do, so I feel like I am always on my own.