Your description of the problem is a little vague; a photo would be immensely helpful. I don't understand the last sentence at all.

Knowing what sort of oak tree it is would help as well. Many live oaks drop leaves in the spring naturally.

Are there spots or discoloration on the fallen leaves?

It could be oak leaf blister, a fungal infection that would come with a wet spring. This won't kill a tree, but you should rake up the dead leaves to help prevent spreading the fungus.

Herbicide drift, or misapplication, could be hurting the tree.

If there are spots on the dead leaves, it could be anthracnose.

Do you see any tan mushrooms around the base of the tree? It might be armirallia root rot.

 The least likely suggestion is oak wilt, as it has not been found in Florida.

Your best bet would be to send in a photo, OR take a sample to your local Extension office: http://santarosa.ifas.ufl.edu/contact-us/