What Causes Persisting Dizziness?

I have been experiencing dizziness now for a prolonged period of c. 3 weeks. I thought it was BPPV, but visited a physiotherapist who specialises in vestibular dysfunction and he told me it wasn;t BPPV, but that my brain requires re-calibrating - for this he prescribed exercises. Now, I have had a swelling (not sore, no trouble) on the left side of my neck for some time. My GP ran tests (negative) and put it down to my being slim and the fact that this sometimes can occur. Would this swelling be anything to do with my feeling dizzy?