Hey thanks guys,
He's moving around okay, the swelling has gone mostly but still not using it much. I spoke to my brother in law who breeds a variety of birds and he said basically the same. He hopes the new bird has just caused a muscle strain while trying to sort out the heirachy but I can get to the vet on Thurs so fingers crossed.
I'm wondering what I can actually do for my budgie to help a possible muscle injury until I get to the vet. He isn't really weight bearing on his left leg but appears able to. His leg and foot appear fine and are not causing him distress apart from the limping. He displays lower movement abilities in his foot then normal i.e. not gripping or stretching it as much. There is swelling above his leg, I guess this would be his hip area. I only noticed this yesterday but last week I did notice he was sleeping on one leg which is unusual for him. I wondered about splinting it but as his leg is not broken I didn't think it would help much. I just don't know how you immobilise the hip area of a budgie to help it heal!