By the time my eldest child was 3 month's old, we were going frantic because of his feeding habits. He was barely taking 2oz. of milk at a time, and refused almost every teat I could find. In desperation, I used some descaler to clean out the steam steriliser, although it looked perfectly clean - and was horrified to see a greyish residue form on top of the water. I just KNEW I'd found the problem, and as soon as I reverted to the old-fashioned method of heating the bottles up in a pan of boiling water and scrubbing them, my son duly drank all his feeds. I wrote to the makers of the steriliser, & had to send the item back for testing. Although they wouldn't admit liability, they refunded the cost of the item and sent me a vouched for �250. I told other mums who'd had sicky/poor-feeding babies, & they also found that once they'd reverted to boiling their bottles, the problems disappeared. Don't know if this'd help in your case.