Neck lumps

Hi , a about a month ago I noticed a small circular lump underneath my ear which I was conscious off but not too worried. Two weeks later I have now noticed on the left side of  the centre of my neck a oval type , movable and quite squishy lump. Which is around 1.5cm in size but a lot bigger then the one underneath my ear. I have been giving antibiotics by the doctor and the lump hasn't shifted in size at all. I have also been feeling quite tired the last few months before I found this. 
I'm a 18 year old guy with no health conditions. Don't smoke or drink and is pretty fit and healthy. But becoming concerned.