You need to hire a very good DUI attorney if you are dealing with a refusal. The officer can ask for you to do the SFSTs and if you agree to do them, you have consented. You also had the right to tell the officer that you did not wish to dance on the side of the road like a trained monkey but you didn't. Additionally, you admitted to having consumed alcohol. There is no legal requirement for you give a confession. Based on your confession and your performance on the SFSTs, the officer can likely establish his probable cause for the arrest. This is why you need a very experienced DUI to fight your case.
The simple answer is yes there could be grounds to further in investigation under 4th Amendment law. You need a great DWI lawyer. Not just any criminal defense lawyer, but one that truly knows the ins and outs of DWI/DUI Law.
While I don't practice in TN, in CA the FSTs are 100% voluntary, so the officer can't necessarily "make" you do them. However, in the facts that you've described, the officer can certainly ask, and it sounds as if you agreed. There is much more to your case though. Hiring a locally experienced DUI attorney will give you the best chance of beating the case and/or mitigating the charges and punishment you are facing. Good luck.
In Tennessee, a police officer can ask you to voluntarily perform field sobriety tests assuming there is a legitimate traffic stop. You may refuse those tests with no legal consequence. Many times, the field sobriety tests will help law enforcement prove their case against you and give the police even more cause to require you to give blood or a perform a breathalizer. If you refuse the implied consent, you are usually not offered an amended offense in court such as reckless endangerment or reckless driving. Usually you are offered a DUI with the minimum DUI penalties and the implied consent violation is dismissed. Also, an interlock device will likely be required on your restricted license since there was an accident involved.
This is general advice and does not create an attorney-client relationship.
A roundup of the best tips and legal advice.