To prove a case involving bed bugs, you need documentation to link the bed bugs to their source and prove your exposure. For instance, if you found bed bug bites on your body the night after you stayed at a hotel, you should save the hotel receipt. Also, take photos of your bites and note your symptoms.
If you can show that the bed bugs are still at the hotel or location of your exposure and subsequent injuries, you have a much stronger case to link your bites and bed bug exposure to their place of origin. If your own home now has bed bugs, or you had to eradicate them from your home following exposure from elsewhere, you'll need to document your costs related to the infestation.