Poor little lamb, and poor worried you
Abscesses really need to be kept open for a few days to allow the pus to drain out. I would lance it again and then flush it 3or 4 times a day( if possible ) with dilute betadine. Keep it covered in between flushes.
A poultice for overnight for a couple of nights will help draw some hard to flush areas.
A poultice can easily be made by placing a thick wad of cotton wool soaked in dilute betadine against the abscess. Then a dry wad placed on top of this. Bandage in place and remove 12 hours later.
The idea is that the dry cottonwool PULLS the moisture into it, which in turn PULLS pus and debris from the infected area into the wet
HTH
Good luck, and hope little one improves