Question about thyroid, or thyroid question =D?

ok, tuesday i went to the doctors and my doctor was going through my symptoms, and right away she asked if my thyroid gland was always swollen. i replied "it's always looked like that?" because i have never known anything different. she felt around on my neck and said that my gland was defiantly very swollen. they did a bunch of blood work and said that she would contact us when she had any information. she said that i might have an overactive thyroid, i was wondering if that can run in the family. my grandfather had to have his thyroid removed because he had an overactive thyroid and medication wasn't working for him. i've noticed that where my thyroid gland is gets sore sometimes. she said that it was a high possibility because i'm underweight and VERY underdevolped =(. so, if anybody has this problem, can you tell me some signs and symptoms of an overactive thyroid? or a website that can give me some info? thanks~!