Since it is a long standing neck swelling not responding to medications, ideally you need to do a USG guided FNAC which means while doing the USG, the sonologist pricks a needle in the most representative part of the swelling, withdraws few ml of fluid which is sent for cytology testing (FNAC)
Next Steps
send both the reports USG & FNAC via chat, futhur treatment depends on these reports
Health Tips
keep an eye for appearance of any fresh symptom and inform accordingly