Hi.. Thanks for the query.. It seems that you are suffering from viral infection caused by Herpes Simplex Virus 1 causing cold sores.. The small lump under the chin seems to be due to swollen lymph nodes secondary to infection.. I would suggest you to consult an Infectious Medicine Specialist and get evaluated and a thorough clinical evaluation and blood tests can help in diagnosis and treatment can be done accordingly.. You can be advised to take a long term course of anti-viral medicines like Acyclovir and also apply a topical application of anti viral ointments like Valacyclovir [Valtrex].. Do warm compresses over the lymph nodes.. Avoid intimate contact with other individuals as it is a communicable infection and spread through close contact with infected individuals.. Hope this helps.. Regards.