Thanks Pedwardine for your support. Dylan has not normally been the quiet one of the bunch and thats why I have noticed a difference.
Have just given him 150ml of energaid in an attempt to get some calories in and he took that surprisingly well. Mandy, we checked his mouth when all this began but could not see anything untoward. His belly does seem a little more rounded than his brother but he is tucked up from behind so this is pushing everything forward. None of them seem to be even attempting the creep even though it is on offer and the hay isn't going down much either. Like I said, they have access to a run with grass so do you think he could have overindulged and is suffering the consequences as he doesn't seem interested in that anymore either.
I'm feeling a little more optimistic since initially posting my thread as he took the energaid well. He's snuggled up with little Mavis under the heat lamp now with a relatively full belly, albeit not milk. Fingers crossed.