My fiancé and I have been caring for a baby squirrel we found for 3 weeks now. 3 days ago we noticed he stopped using his left arm, and his arm and left cheek were swollen. He looked normal in the morning, and it did not show up until the afternoon, he had not fallen or been dropped. We thought it was maybe a bug bite as we let him crawl around outside supervised, but it’s 3 days later and he’s only slightly improved.

Any ideas on what it could be and how to help him? He doesn’t seem in pain, and responded normally when we applied pressure to his injured paw.