So I've been breastfeeding and formula feeding my 5 week old . He spits up a lot and has a lot of reflux . But he also goes days without pooping . He becomes extremely fussy and uncomfortable . I tried switching his formula to enfamil AR for his spitting  up which has helped . But he still won't poop . Should I take him to the doctor . Or should I try switching the formula to enfamil reguline which may help regulate him pooping ? I need help moms .