Fussy baby at night

FTM and looking for some advice.. So my 3 week old has been super fussy at night between 3am and 8am. Ill change him, feed him, soothe him as much as I can and he'll seem OK for a few but then he'll loose him mind and get upset. He's not to fussy during the day so I don't know what's making him unable to sleep like he does during that time. 😦

We have a doctor's appointment coming up in a few days but does anyone have some advice or something I could try in the meantime?