Hello and welcome to healthcaremagic. I am Dr Asad sami.I have read your question and i can understand your concerns.I will be answering you. What is your age..?? For how long the lump is there..?? Is it hard,firm or soft..?? Is it increasing or decreasing in size..?? Does it pulsate..?? Are you loosing weight..?? Does it cause pain when you eat..?? Does it move upward and downward while swallowing..?? Any family history of submandibular gland tumor..?? Any history bad odour from mouth(halitosis)..?? If were treating you in my clinic I would have examined that lump to look for its consistency and its relation to structures such as muscles, mandible and submandibular gland.I would have examined your oral cavity to look for any stone formation in the tonsills(tonsillolith) as you mentioned that you have chronic tonsillitis.stone can be removed by forceps and for chronic tonsillitis causing problems,tonsillectomy is the treatment of choice. I would have palpated floor of your tongue to look for any stone formation in the duct of submandibular gland(warthins duct).this condition is known as sialolithiasis.In this condition the duct is closed by stone formation and thus the gland swells and lump is felt under the mandible.for its diagnosis sialogram is the investigation of choice.the stone can be removed surgically. I would have done fine needle aspiration cytology of the lump to look for the cause of swelling , whether it is benign or malignant,whether it is lymphadenopathy(enlarged lymphnodes caused by tuberculosis,lymphoma,leukemia or any head and neck infection.) or mass arising from muscle..I would have ruled out lipoma,sebaceous cyst.In fine needle aspiration cytology it will be evident whether it is benign or malignant condition arising from submandibular gland..other conditions to rule out are aneurysms which are abnormal dilatations of arteries. I will suggest you to meet an ottolaryngologist or a general surgeon for a second opinion.in the mean time remain calm. Thanks. Hope the answer is helpful. Feel free to ask further questions. Regards.Dr Asad sami