Most thyroid nodules don't cause signs or symptoms. But occasionally some nodules become so large that they can: 
Be felt
Be seen, often as a swelling at the base of your neck
Press on your windpipe or esophagus, causing shortness of breath or difficulty swallowing
 In some cases, thyroid nodules produce additional thyroxine, a hormone secreted by your thyroid gland. The extra thyroxine can cause symptoms of an overproduction of thyroid hormones (hyperthyroidism), such as: 
Unexplained weight loss
Increased sweating
Tremor
Nervousness
Rapid or irregular heartbeat
 Only a small number of thyroid nodules are cancerous. But determining which nodules are cancerous can't be done by evaluating your symptoms alone. Most cancerous thyroid nodules are slow growing and may be small when your doctor discovers them. Aggressive thyroid cancers are rare with nodules that may be large, firm, fixed and rapid growing.