As you have mentioned the lump is mobile, soft in consistency and it's there since November 2019. I would like to know has the lump increased in size since November and are you having any other symptoms like fever?
Usually a soft mobile lump points more towards a lipoma. To be sure about the nature of the lump, you may go ahead with a USG guided biopsy (though the lump is not that big 8mm × 5 mm). The histopathological examination will reveal whether it is chronic inflammatory or not.
Next Steps
May plan for USG guided biopsy.
Health Tips
Check for such lumps anywhere else, like in the axillary area (underarms), inguinal area (groins).