Looking for some advice please

Aiden is usually a poo a day baby! He is boobie fed and has one meal of solids daily for the last month.... but now he hasn't poo'd for 5 days! he doesn't appear to be in much pain - a little grizzly maybe.. I tried a little water (with a tiny bit of brown sugar), infants friend and prune juice ........... we have some small little mushy carmel poo (which that they smealt like carmel!) buds - but thats it. I am getting a little concerned that I should take him to the doctors.......... Do any of you lovely ladies have any advice?

thanking you all in advance