My Fiancé Got A Knot On The Back Right Side

My fiancé got a knot on the back right side of her head last week, we're not sure what it is.
Her symptoms are dizziness, always tired, it's tinder to the touch (not the knot itself) just the surrounding area.
She said last night she was able to touch the bump and be able to move it alittle.

My thinking is a cyst. I have one on my leg and know they are squishy.. But I'm no doctor or anything so I'm coming here for answers. Thanks