I went to the doctor now waiting on blood tests results.?

Hi, I went to the doctor today because for the past week or two I have been feeling off. On and off I wake up with joint pain and chills but low grade fever with rapid heart beat and my chest hurting. When I get started during the day I usually start to feel better. I can go two days feeling fine then boom it feels like I am coming down with something. I have been having bad allergies all month long or so. I also have a small swollen lymph node in the back of my neck. Flu test came back negative but my doctor tested me for mono. I had it when I was 14 years old or so. I am still waiting on my results. He feels my lymph node is from whatever I am fighting because I told him I am concerned about lymphoma. He feels it’s just from the allergies and possible infection. So I am hoping nothing is seriously wrong. Question should I worry about lymphoma or could this be from allergies or mono? He said allergies can make your body shut down too in the sense of feeling like you have the flu and this year it is really bad. Well pray I get good results! Thanks