hi Welcome to healthcare magic forum !! From your description, it looks like either you have a pyodermic lesion over your neck or it is a case of vector dermatitis.... In either of these, there can be development of a painful swelling over the affected area with oozing of fluid at places...The yellowish liquid can be pus discharge from the infected lesion... Now firstly i would advise you to keep the area clean and dry as much as possible...Do not apply any kind of moisturizing creams/lotions or oil over the affected area... Clean the area with lukewarm water or give warm saline compresses twice a day and apply an antibiotic cream like mupirocin gel over the area twice daily... If inspite of the above measures, the lesion persists or continues to increase in size, then you might need a course of oral antibiotics along with pain killers..In that case, i would advise you to visit a dermatologist for proper assessment and treatment Hope it helps Dr Geetika Paul