Swellen cervical lymph nodes. My case.

Hi Doctor, i have 3 swollen posterior cervical lymph nodes in left side of my neck, i notice this is February 2018, on 6th May 2018 i went for ultra sound and my report mention that i have bilateral sub centimeter lymph nodes, my GP told me nothing to worry and he ask me to monitor it, if size increases it need to be further investigated. 10 days back i got left ear infection and i notice these lymph nodes are increased in size, yesterday i went for another ultrasound i found 2 large lymphnodes of sizes 12mmX4mm & 9mmX4mm. this time doctor gave me antibiotics for 7 days and he said nothing to worry and it will become normal with medication. i am very much terrified because when i google i found more than 1cm size of lymphnode is suspicious,  kindly can u help me to understand what could be the reason of sudden increase in my lymphnode size, and what are the possibilities of malignancy in my case. Thanks, Faraz ahmed