Swollen lymph nodes on a 20 month old

My 20 month old son has swollen lymph nodes on the back of his head, neck and groin area. His pediatrician did a CBC and his lymphocyte count was elevated but there were no signs of "blasts" (I don't know what that means). He has had them for 4 months now and he is always cranky and runs a mild fever often. She said to keep an eye on him and she would re-check him in December when we have his 2 year appointment. I'm worried if it's something like cancer that I'm letting precious time go by. Should I see an ENT for this?