hello and welcome to HCM,
In all probability your husband seems to be suffering from an infection.
The lump can have different reasons and diagnosis.
But in the background of the lump in his neck and the persistent pain you need to definitely seen an ENT who can give you a proper diagnosis and treatment.
he may plan to wait and watch after prescribing medications or may evaluate the lump further with blood tests or FNAC or probably biopsy
meanwhile avoid spicy and cold
Do not try to palpate or meddle with the lump
Do not try to self medicate
take care and get well soon
Dr Sriram Nathan