Glad to see you made it here from the General board, dawnie.
IMO, they're sending you to the wrong kind of specialist, but I understand that without insurance, you probably have to go where they tell you to? If I'm wrong about that, and if you're going to have to pay this guy out-of-pocket - if I were you, I would cancel the appt. You actually need to see an endocrinologist. That's the speciality that deals in thyroid diseases. No sense wasting money on someone who removes things from bodies for a living if you don't need anything removed from your body. That's JMHO.
Your dog probably didn't have anything to do with the problem, except he called your attention to it. That is, the gland was probably swollen but you hadn't noticed it until he hit it. You have the most common symptoms of overactive thyroid, called hyperthyroidism. Weight loss, fast bowels, anxiety, thyroid swelling... It all fits the picture.
You can't let this go. I think you said you're a young woman, right? And without insurance... that's the pits. But you need to do whatever you need to in order to see a doctor for this. It can be life-threatening if it goes untreated for very long. If you absolutely have no where to turn, go to the ER of the nearest public hospital. I believe - although I may be wrong - that they aren't allowed to turn anyone away in an emergency. (You can embellish your symptoms a little if you have to.... Overwhelming anxiety, weight loss, fast bowels, and a very sore neck should do the trick.
) Or call around to all the public health clinics in your local phone book. Most communities have help for the medically uninsured. Anything... just don't let this go, wishing it will go away.
Whoever you see... if they try to rush you into any drastic treatment with the intention of destroying your thyroid gland, don't buy into it just yet. Take time to inform yourself about your options. You can always ask here for whatever you need to know. Someone is always around with sound advice, or we can recommend expert authors and books for you to read.
Please let us know what happens tomorrow. We'll be pulling for you.