Baby is 8 weeks old and formula fed. So far they've been a happy content baby no issues until now. They've started becoming 'fussy' the same time for the last few evenings and it lasts about an hour before they fall asleep. Loud crying, arching back, wanting milk but then spitting the bottle out, and loads of gulping/swallowing noises. They seem really uncomfortable and crying like in pain and unlike any other cry they do normally. They only do this in the evenings and not at any other time. Any advice welcome 