I am 28 years old. I have a cyst in left side of my neck from last 15 years it used to swell once or twice in a year but now a new cyst has developed on the floor of my mouth on left side which drains pus from one of the two passage under the tongue. I have take amoxyclav 625 twice daily for 10 days and my pus was stopped completely but after 5 days it again started to drain pus. Pls help me and tell me what the problem is? Is is cancerous? Is it a medical emergency?