Here are some possible reasons for a hard lump:
* Abscess: This is a common problem in goats and can be caused by a variety of things, including puncture wounds, insect bites, or foreign objects.
* Tumor: While less common, tumors can also cause lumps in goats.
* Inflammation: A variety of injuries or infections can cause inflammation that leads to a hard lump.
* Injury: A direct blow or injury can cause a hard lump or swelling.
Please do not attempt to diagnose or treat your goat yourself. A veterinarian will be able to assess the situation and recommend the best treatment plan for your goat's specific needs.