My baby is so fussy, I thought he seemed like he felt better but again around 9pm he started to get…

My baby is so fussy, I thought he seemed like he felt better but again around 9pm he started to get very fussy again. He's eaten and has a clean diaper on. Idk what to do he keeps waking up after sleeping for 15 or so minutes and cries and cries. I'm so upset I feel like a bad mom because I can't help him.