I'm currently going through investigation of a lump at the back of my neck and would just like to hear others experiences and opinions.

I've had a slow growing, solid , not painful lump growing at the back of my neck, directly over the spine , realistically I've left it too long before going to the doctor, it's probably been there 2 years or so but very slow growing and still not very big.

Initially one doctor wasn't keen on actually seeing me and diagnosed a cyst over the phone , managed to get seen recently who mentioned both lipoma and lymphoma and I'm now just very confused about what's going on and what I should do as my doctors are in full covid booster mode and not especially easy to get hold of .

I've had various odd symptoms such as night sweats, dizziness and vertigo , fatigue and breathlessness .

Had one set of bloods done which apparently came back okay but don't actually know what they tested, doctor has sent me in for another set of bloods in the next couple of days .

The first doctor to see me said they would do a ultrasound to rule out anything suspicious but this seems to have been forgotten about and when I've now spoken to the last doctor, a different one to before, they've just said they'll message the other one . 
I'm kind of taking their lack of urgency as a sign they're not concerned but at the same time I've got a strange set of symptoms and my main query with the lump now is that I'm fairly certain it changes shape and size, feeling slightly smaller sometimes etc , and as far as I'm aware a lipoma wouldn't do that ? 
Sorry for the long post, I don't really know what to think or expect and would like to hear of others that may have had similar experiences .