My 4 1/2 month old daschund started showing symptoms of swelling on Thursday night. Her lips were the first to show signs, and soon after her eye lids. I took her to a 24 hour vet, who gave her a cortisone injection, and advised to take her home. The swelling subsided.

Friday morning we awoke to find that she was swollen up again. We returned to the vet, who injected cortisone again, and gave a painkiller to take home. The vet is adamant that the puppy has been stung or bitten, or eaten something it shouldn't have.

Friday she spent the entire day in my arms or on my lap, and for 1 hour was on my dad's lap. She never had a chance to to anything unsupervised. When returning after an hour, she was swelling up again, and again went back to the vet Friday night (1am). Another cortisone jab, and she stayed over with her vet (infact in bed with the vet).

Saturday morning we collected her (10am) and she was fine. Last night she showed symptoms of her ears also now swelling, and gave her cortisone tablet, which helped.

This morning she seems fine again, although her gums still seem to be swollen around her teeth.

Any clues as to what could be ailing her?

HI,
I am not a Vet, but I do think you need to consult with a different Vet. If we have a health issue ourselves, and one Doctor doesn't help that much, we get another opinion.
It could be a bite, or could be something else, or could be allergies to something.
Weird things like this sometimes to lead to an allergy.
I do wish you the best, and good luck.

Just a question, but have you changed her food at all recently? Or has anyone maybe slipped her some table scraps? Recurrent swelling such as this suggests allergy. I would demand blood tests if the symptoms persist