No one would be able to tell you anything with any assurance without a scan of some kind; do not ignore the feeling. Your description of feeling something that is not visible to you does not mean something is not there; insist on a scan.
It could be a number of things, coming off the pred is one, could also be anxiety; however, it's always worth getting your thyroid checked.
You should get a thyroid panel, consisting of Free T3, Free T4 and TSH; you should also get tested for thyroid antibodies to determine if you have an autoimmune disease, such as Hashimoto's Thyroiditis or Graves Disease. You should also get a thyroid ultra sound to determine if your thyroid is inflamed and/or has nodules.