thank you very much for your advice that makes me feel a lot better :]
Fatty tumors and cysts are very normal, nothing to worry about. If any pop up that aren't very movable, rock hard, or grow unusually fast, then I would have them checked out, even then they may be nothing. Sometimes a cyst will pop on its own and need to drain and be cleaned.
Benadryl is quite often used in dogs, it is given according to weight. Weigh her at home and then call your vet and ask what an appropriate dosage is for her size. Some dogs may get very drowsy with it, but it is fine for them. :)