Has anything other than TSH been tested? TSH 0.3 is low but it is low-normal.
The mass is likely to be thyroid nodules. 95% of thyroid nodules are benign so it is unlikely to be malignant but it is protocol to check nodules >1.5cm to be sure. Thyroid nodules and thyroid cancer are usually asymptomatic and are unlikely to have caused the symptoms you describe.
Have you had ferritin, vitamin D, B12 and folate tested? Low vitD can cause bone and joint pain and low B12 can cause pins and needles and dizziness and anxiety.
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