7 week old hasn't pooped in 2 days

My baby boy hasn't pooped in 2 days, he is formula fed and seems to be uncomfortable and is tensing and pulling his knees to his tummy. Before these 2 days he was the same but was having 1 bowel movement every day, our health visitor told us this was normal because his dirty nappies where runny and a normal colour.. I've tried bicycle legs, tummy massage and some cool boiled water.

Any advice on what else to do is more than welcome, I want to try anything to help my baby😢