Summah, has his length changed a lot since 4 weeks ago, maybe he just had a growth spurt? It is also very common to start waking through the night again in between 4 and 5 months of age. Does he have heaps of wet nappies? Is he happy? I am no expert on this but just wanted to give you a great big , it is so hard if you can't see how much they are getting, I hope that Barb pops in soon to give you some great advice.