My son had a thyroglossal cyst removed also when he was 4-5 they told me the only complication is that sometimes the cyst could refill shortly after surgery. However, I don't believe everything the Doctors tell me. However, my son is fine and it's been 25 years since his surgery.
Which tests did they run on you? Many doctor run just a TSH routinely which misses 80% of thyroid diseases according to a News Report I heard I believe it was on the Today Show 5-6 weeks ago . FT3 & FT4 is a better indicator. Did your doctor run these test for you?
There is a lot of knowledgeable people on here if your looking for answers!
Post yr FT3, FT4 and TSH levels here so others can post. ;o)