Update: I found two signs of injury after a nap and took Max to the emergency vet recommended by @normwilner.bsky.social. The neighbour dropped off flowers and offered to pay for the vet fees, plus the Uber ride here. Max was just admitted to triage. I will also sign up for pet insurance.
My dog Max is nervous of bigger dogs because of a previous owner who did not socialize him properly, and did not train him; also some bad experiences with bigger dogs. So it's not great that a neighbor's Husky-like dog was unleashed, came up to Max, and they got into a tussle in which I fell down.