Baby crying

FTM here and wanted to see what is everyone’s protocol when your baby is hysterically crying. I fed him, and burped him and he started hysterically crying. And i just couldn’t figure out why is he screaming and crying. I even undressed him to see if i can see any physical signs on his body. Tried soothing him and nothing worked. just wondering what do you guys do when your baby hysterically cries and how do you know if it’s something serious or not ?