You did a very good job of noticing the problem and addressing it right away. The poulitice and the bute was a good way to go, and not giving him the bute the second day was good as to not mask a problem. Now it is time to find out what it is, or was. Could he have “hit” this area with the opposite foot while jogging or galloping? Did you have bandages on his front legs, if so were they on an excessive amount of time? Or, did he strain a tendon. If the inflammation went away completely and he is sound, you might be ok. If after the bute and poultice some of the inflammation came back I would highly recommend your veterinarian to look at the injury. If your veterinarian is suspicous of a tendon injury it would be in your best interest to rest your horse and when the inflammation has gone down to have a ultrasound done on his tendon. You really need to know, that if it is a tendon injury, how severe is it? It could be just a strain or something more severe like a tear in the tendon. An ultrasound will tell you exactly what the severity is and where it is located.
Please let us know how everything goes. Thanks!