SweetSerenity,
A picture would speak volumes, but we may be able to figure this out either way. The major contributors to hibiscus health (and probably all plants) are environment, moisture, insects, disease and nutrients.
The first 3 are easier to deduce than the last. Have you noticed any environmental changes in the past few days? Over cast, temp swings, excessive rain or lack of? Next I would look closely for any infestations. Look under the leaves as most hide in this location. Diseases can be a little trickier. If a plant appears droopy or wilted even with adequate water, the roots are diseased an unable to extract fluids or nutrients. Lastly, nutrients usually do not cause dramatic leaf loss. Personally, I would look at the environmental side. If you had excessive rain...drainage might be an issue.
Hopefully this helps.
Ed

Thank you Ed. The temp keeps changing here in Florida this time of year. Cold, hot, cold, hot, masses of rain, windy and dry. It's like that all the time and I can't really narrow it down to one specific event.
Maybe it's the last couple of weeks temp changes that got to it. We had night temperatures ranging from 35 to 60 so maybe that's what got to it?
Luckily it's the perfect time to trim it back so that was good timing.
I did look for infestations but there is none. I guess the weather is to blame.
Thanks again Ed.

SweetSerenity,
I think you found your answer. I would wait until the temps stabilize above 50 before you prune. After a month you will see good new growth. I am an extreme encourager of pruning. To me it is a no-brainer. Tropical hibiscus like it, and it increases blooming areas.
Ed