Suggest Remedy For Swollen Lymph Nodes On Neck

My son is 6 and has had 2 swollen lymph nodes on the left side of his neck. They have been there since Feb 8. Now he also had one on the right. The two on the left seem a little bit bigger than an few days a ago. His doctor ran a cbc w/diff a few weeks ago and everything showed normal. Should I take him in to the children s hospital to have them check him out closer or maybe go in to an ENT like my doctor suggested? My father had cancer on the left side of his neck that help result in his death (I was out of state so not sure exact location of the cancer except on his neck)