Sick 48h after eating, can it be food poisoning?

Yes: Yes, some food-borne bacterial infections, such as salmonella, shigella, or campylobacter, can take that long to cause diarrhea. But it's very difficult--almost impossible--to determine what food you got sick from unless other became sick as well. You presumably have eaten more recently than 48 hours ago, and anything you ate during that time could have made you sick.