I had a pain in my neck. the the pain moved to the left back of my head. i feel like there's a fluid in it. sometimes i feel the fluid in my left ear?

Ear infection: You most likely have fluid in your middle-ear due to Eustachian tube dysfunction from allergic inflammation or infection. Decongestants are helpful but if there is an infection, you will need antibiotics. Another maneuver that may relieve the pressure in your ears is to try to "pop" your ears by pinching your nose, closing your mouth and blowing.If the pain persists, see your doctor.

Ear: Sometimes its a referred pain from the spinal nerves or muscles called a cervical neuralgia, Go see an ENT to check the ear out but you should see a neurologist