You do need to see a doctor and have this checked. They will probably want to do an ultrasound or CT scan to see what's going on with it. They will probably, also, want to do thyroid function tests, which should include Free T3, Free T4 and TSH. TSH is actually a pituitary hormone, but is used, primarily, to test thyroid function because it stimulates the thyroid to produce thyroid hormones.
I'm not sure where you're located, but there are programs with which you can get help for medical problems, in most countries. Tell us where you and and we might be able to help you or check with your local health department.