What might be the cause of some swelling on my neck which I suspect 2B thyroid?

Need 2B seen. Your thyroid gland is located low in the neck, around the level of your sternal notch. Swelling in the neck may also involve lymph nodes, salivary glands or other structures. The list of problems which might cause swelling in the neck is quite long. See your pcp or ENT for a thorough physical exam and appropriate workup.
Many. Infections often cause enlarged lymph nodes in the neck. You should be seen so your doctor can check your thyroid gland and lymph nodes and check for other problems.