It's hard to tell without pictures.
Did the flower open at all??
The flower size being small (when fully open) is not due to watering, but rather genetic. I've seen them from as small as 7 cm across to over 18cm!
As long as the dorsal sepal is round and full, flowers with natural spread of about 13 cm looks very big and nice. Many are just around 10 cm give or take.
I like them really big and glossy!
I see a lot of paphs coming into stores now have unusually small flowers for bulldogs. I was shocked!
Also, many of these bulldogs are horribly crippled.
So, if your flower opened up fully and looked like a "normal bulldog" flower but was just small, then it's just genetic.
turning brown and shriveled up in days can be due to severe underwatering. How often did you water??
Plants might just terminate the flowers on its own for some reason, although I haven't see this a lot. It's just a possibility. Why do they do that? There may be many different reasons.