I've got a 3wk tame lamb with an abscess on his upper lip. I'm confident it's not orf having treated lambs with that last year. He was a bit off colour a couple of days ago so he has had pen&strep every day since but the abscess has come up overnight. He is still drinking but looking a bit lacking energy. It hasn't burst yet, should I leave it and hope the antibiotics start to reduce it (he's just had another jab this morning) or should I lance it?