my baby is 4 weeks

(Rebecca) • Im 33wife married 14 years and have 3 boys 14,9,3

my baby is 4 weeks and hes fussy in the evenings hes fine during the day but in the evening he aeems to get fussy and like cluster feeds and acts like hes starving even tho he just ate he eats 3 to 4 oz we burp him and hes still fussy his formula has been changed idk i think its gas but idk anybody else experience this ?