There's more to testing for thyroid problems than just TSH. It is good that your doctor is doing a scan as a followup on the thyroid swelling. Despite your "normal" TSH, it definitely sounds like SOMETHING is going on.
It might ber a good idea to Check Free T3, Free T4, TPO Antibodies, and Thyroglobulin antibodies as well, and this is something you should likely discuss with your doctor.
I am not a doctor, nor have I ever played one on TV...