Can I suggest you give the ABA a call? One of their counsellors will be able to go through with you all the reasons why this could be happening. IMO, 5 weeks is a little young to be going 10 days between poos. It would be good to clarify whether or not it is actually a problem. Hopefully Barb will pop in and give you some advice too

Oh, how many times does your bub feed in 24 hours?