Hi.. I have a 6 week old baby boy ive been form...

Hi.. I have a 6 week old baby boy ive been formular feeding for 2 weeks now..First baby and iam bit unsure.. He sometimes poo's dark green and grey alot in one go very pasty need about 10 wipes. but when he does he is in pain for half the day crying hard to settle... before he He is on Nan gold ive also tried s26 ... I here some babys get lactose intolerant are these signs???