If you can get him back to your vet. The yellow indicates that he is becoming jaundiced and would need to be put on fluids to try to flush his system out. They should retest his liver values and see how much they have increased. They can also force feed him to help get him back up to speed. This could be a combination of the stress from the abcess, antibiotics and the liver problems. His system may not be strong enough to deal with all these problems at the same time.
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