I’m glad to hear he ate the block. There is no reason the block would cause an issue for him. Maybe he was just full and needed to rest.
One thing that concerns me is his age. At 10 he is an older squirrel. Of course they can live much older but I get concerned about issues related to aging. They are subject to any of the organ failures that can happen to any other mammal, including us. Lumps and masses are concerning.
For now, getting him eating healthy foods, addressing potential MBD and if needed treating for parasites are areas that you can address.