HELP. Swollen lymph nodes for months

So I've had two swollen lymph nodes on both sides of my neck right underneath my chin for at least 3 months possibly 5. They're hard as a rock and don't move. I had a pretty severe stomach virus in July where I had to go to the ER and was put on some tough antibiotics. I think/hope this is when they popped up but not sure. I saw my doctor about it last month. He confirmed they were swollen and ran blood work, everything came back normal. He said to just not worry about them and stop touching them. I cannot stop worrying about it. I'm really scared it's lymphoma. Anyone else have this happen?