Goitre on my neck is causing a lot of pain, tried paracetamol, ibuprofen, cocodamol etc and it's not working, are there any other strong painkillers?

Pain: The tissue swelling can be a source of pain. Treating the underlying goiter is paramount but for the pain the use of anti inflammatory medications would help with swelling and help with pain. Stronger medications such as low dose vicodin or ultram may be required to help sleep.

Not many good option: A symptom of autoimmune thyroiditis is pain and tenderness. Nsaid drugs and Prednisone can help but unrelenting thyroid pain may require thyroidectomy for resolution. There is viral thyroiditis which has pain that improves with steroids and narcotics. A rare form of bacterial thyroid infection exists but these patients are very sick with high fever. See endocrinologist or thyroid surgeon.