Sorry for not been on, been a bit of a hectic weekend.
I don't know about Creon at that age if I'm honest all you can keep doing is going back to your child's doctor. Creon is a bit of a juggle and can take time to find the correct dose. They can do a fat test which tests the stools to see how much fat is being digested, as a child I had this test once a year to make sure my dose of Creon was still adequate or if it needed adjusting.
For the weight issue, if your child is growing quickly then it could be taking extra energy aswell as babies are usually really energetic at that age so could be burning more calories off. You can try add more into his diet but with his age I would really advice seeing a doctor, or even better a dietician to discuss what can be done to help him gain weight.
Sorry o can't be much help
Moderator of the Cystic Fibrosis forum
Hey, I'm Gem with CF, age 29 and diagnosed at 2 years old. I'm no expert but having CF myself I've learnt a few things along the way.
Diagnosed with: Cystic Fibrosis, Asthma, ABPA, Clinical Depression, Mild Liver Cirrohsis, Mild Osteopenia, Erythema Nodosum, Proximal Myositis, Polyarthralgia