Check out this thread for more info on thyroid problems.
Your GI guy is not the right doc for thyroid. At a minimum, you need a GP or Family Practice physician who can do the whole series of tests. At best, you need an endocrinologist. My endocrinologist does: TSH, T3, T4, and T3 Uptake regularly and did a whole slew of other tests when we were still in the diagnostic stage. Take a look at one of the books mentioned in the thread I referenced above.
Your GI guy is also not your best line of defense on ovarian cancer. Here I'm not too knowledgeable, but my understanding is that if your gyno did an exam, that's your best test. If you're unsure, call your gyno's office, tell him you've been tentatively diagnosed with IBS and that you know you must rule out ovarian cancer, and ask him if the exam(s) he has done are sufficient to do that. If you're young and if you have been suffering from IBS symptoms for a while (rather than having a sudden onset), he'll probably think you're a worrywart, but do it anyhow for your own peace of mind.
I already gave you my thoughts on finding a new doctor - I'm sorry none of them panned out for you. I'm lucky to have a very good Family Practitioner and Endocrinologist, and I have high hopes for the GI guy I saw last month - it's still too soon to be sure about him. He's one of the GIs who can prescribe Lotronex and it occurred to me that looking for GIs who can do that might be a way to find a good one, but I haven't been able to find a list of them on the Web. Maybe somebody else can.
-------------------- [Research tells us fourteen out of any ten individuals likes chocolate. - Sandra Boynton]