Lymph nodes enlarged on neck

Hi everybody, I have been having two big lumps at the back of my neck for weeks now. Over a month and more because I don't think I have noticed them straightaway. One is right behind my left ear and the other one more in the middle. Not painful. 

I don't have obvious signs of any infection and I don't have a fever (took my temperature).

I have 0 energy all the time but this has been for years now. I suffer from undiagnosed hypothyroidism. 

I have an appointment with my GP tomorrow morning so I will see what she says but do you think I need to worry? 

I have felt my neck and I feel other little lumps around my neck. I assume it's my lymph nodes. 

Only thing that bothers me is occasional nausea and dizziness. I have vomited a couple of times recently without being ill with something. I put that down to my GERD.

I am always cold and my skin is very dry so I do itch but I can't say more than usual. 

 

What have people experienced when they have had lumps on the neck that turned out to be lymphoma?

Does a blood test show it or can you have normal blood tests and still have it? 

 

Thanks for any reply in advance and good luck to anyone who is worried about a possible bad outcome.