You can never have enough...

[Mica]

I have a query about my dog Stella, every morning now she wakes up with a swollen throat underside of her mouth and also her upper and lower lips are tight and swollen, by the end of the day the swelling is much less and then process repeats the next day.

Just paid $500 at the vets for a diagnosis of water retention due to heart murmur and given antibiotics, anti-inflammatory and diuretic, no real improvement.  This is the 4th day now, in fact I think it is getting worse.

With the wealth of experience here maybe someone has seen this in the past in their animals?

Trying all possible elimination due to allergies, sure it is not due to bee stings because of the fluctuating repeating everyday, she spends all her time with me and I am watching closely but nothing obvious re eating or encountering any toxic substance or animal.

Stella has pulled interesting  symptoms out of the bag hasn't she.
How old is Stella and what breed is she?
Lots of causes of oedema, what you describe sounds quite , localised too. Unusual conditions often  it is a matter of elimination to get a diagnosis. I presume all her blood work came back normal and that the heart murmur is something that hasn't been detected before at her annual health checks.
If there is no improvement after a week I would be taking her back sooner if you think the symptoms are getting worse, if you think it is allergies there are vetterinary dermatologists that do allergy testing or sometimes allergy meds might be given to see if there is a response.
I hope Stella improves soon and it is not bothering her too much