Being 25 lbs lighter will affect your tolerance for sure, and age will do that to you too. It may be time to back off on the beer benders, even if they aren't frequent. The 4 lb loss is likely dehydration from the upchuckfest. I'd eat as normal, if it was stomach flu and not the beer, eating too much will just make you sick again, and you probably don't really need it anyway.
If I keep starting over, eventually it will stick, right?
Current weight: 140
Goal weight: 135