I work in the same field as you (heme/onc/bmt) and there is no doubt that just working in that specialty will lead you to fear the worst. Given your background, you also know that there are a million and one other things that can cause swollen/achy lymph nodes including minor infections, allergies, and many other benign conditions. Perhaps you need to get a second opinion from someone other than your GP-- I think it would really help put your mind at ease. Also, if your labs have been normal, that should also provide some reassurance. Take care.
Do you have any other symptoms ?