Worried about a small lump on my right side on my neck

Hi, 

I'm a 22 year old female. 
 

Today I have noticed a small lump on my neck. It's feels like two small balls next to each other and they feel hard. Recently I have had a lump under my armpit aswell but this seems to come and go. 
 

I haven't been feeling unwell but very tired. But I have been working very long days the last 2 weeks at work so I think it is just that. 

I was just wondering if anyone had any advice on what they think it could be and should I go to the doctors or wait a few weeks to see if it goes as I've only noticed it today? 
 

Many thanks 

Annie