I changed my daughters formula from Aptamil to Cow and Gate Saturday morning and since then she hasn't pooed! She normally goes every day or every other day at the longest! I only changed her formula as I'd just about had it with all the runny poos from Aptamil. Every poo nappy would be major runny and would go all over her clothes So thought I'd switch to C&G but now she doesn't go at all! I've never needed to switch formulas before so have been doing half and half of each formula in each bottle. Should that be ok or should I have introduced it more gradually? Any advice? Should I give it a bit longer or switch back?