lymph node on neck, night sweats, fatique, weight loss...

I've had a lump in the back of my neck for quite some time now (2 years). I never really paid much attention to it as I thought it was just a cyst or something, and there was no pain associated with it. Last week, I saw my GP because I could not move my neck and my back was really sore; as he proceeded to examine me, he noticed the lump on my neck. Asked me several questions, he was more concerned about my lump then he was with my back he said. due to the fact that I had ansered yes to most of his questions, like night sweats, fatique, weight loss with no apparent reasons. with that being said he is sending me for an ultrasound, Should I be concerned???

I am a 43 year old female, for the most part very healthy. Not sure what to make of all this!!!