My dog just got attacked!!!!?

I took my little labrador cross border collie puppy to the feild near my house and we had him on the lead hes only 16 weeks old, and this lady with her 2 dogs just arrived when we did. She had a little jack russell and a springer spaniel which was still a puppy but he was huge. The springer spaniel came charging up to my dog and starting showing his teeth and barking, my dog quickly lied down and he was frightened. Then the springer spaniel pounced on him and was biting him viciously and my puppy started yelping and screeching. The owner of the springer spaniel was just standing there trying to call her dog so i quickly tried to push the springer spaniel away but he came back to bite my puppy again so i grabbed it around its neck and dragged it away and i was holding its neck tightly so it couldn't move its head, my puppy quickly ran away and he was yelping. The owner of the springer spaniel said shes ever so sorry and she took her dogs and left straight away. I checked to see if my puppy was ok, i dont think he was bleeding. After his walk i took him home and now hes just lieing down. Im not sure if hes hurt what should i do?