I was an Audiology Major
A blocked eustachian tube should not cause all the symptoms you are describing. What you should mostly see is the feeling of fullness in your middle ear (vacuum otitis media) Posible fluid in the middle ear (serious otitis media) and sometimes but not always a middle ear infection caused from the above two (acute otitis media) With these there will be some hearing loss, up to about 25 db.
The middle ear where the eustachian tube is connected to is a small space which houses the three bones of the middle ear which connects the tympanic membrane to the oval window. The three bones act as an amplifier for the sound waves entering the hearing apparatius.
Balance issues (vertigo) Headache, motion sickness is not usually middle ear. This is inner ear vestibular involvement. It is possible to have a inner ear infection that can cause these symptoms, as well as other issues and syndromes. One of the most common causes of balance issues is elevated blood sugar (diabetes).
I would ask for another opinion, you may also ask for an audiometric exam, a tympanogram will tell you if there is any compliance of the tympanic membrane and thus give an idea of the middle ear health and patiency of the eustachian tube.
If inner ear, vestibular involvement is suspected your doctor could order a ENG, Electronystagmogram. This is the gold standard in testing inner ear disorders.
Below is some information I cut and pasted.
How is Eustachian tube blockage treated?
There are several maneuvers that can be done to improve Eustachian tube function. The simple act of swallowing activates the muscles in the back of the throat which help open the Eustachian tube. Chewing gum, drinking, or eating promotes swallowing. Yawning is even better because it is a stronger muscle activator. If the ears still feel full, you can try to forcibly open the Eustachian tube by taking a deep breath and blowing while pinching your nostrils and closing your mouth. When you feel a pop, you know you have succeeded. If problems persist despite trying to forcibly open the tubes, you may need to seek medical attention. If you feel dizzy performing this maneuver, then stop and discuss this with your doctor.
If you have a cold, sinus or ear infection, or suffer an allergy attack, it may be advisable to postpone a trip by airplane. Similarly, individuals with Eustachian tube problems may find such sports as scuba diving painful, and in some situations quite dangerous. Babies traveling on airplanes cannot intentionally pop their ears, but may do so if they are sucking on a bottle or pacifier. While descending on an air flight, it is best to feed your baby and not allow him to sleep.
Many air plane travelers with Eustachian tube problems use a decongestant by mouth or nasal spray an hour before take off, and, if necessary, prior to descent. The decongestant acts to shrink the membranes lining the nose and throat, allowing the ears to equalize more easily. Similarly, patients experiencing chronic daily problems with Eustachian tube dysfunction can benefit by aggressive control of allergies (antihistamines, decongestants, and prescription nasal sprays). Allergy evaluation can be helpful. In severe situations, a tube can be surgically placed through the eardrum, replacing the role of a functioning Eustachian tube to equalize the ear pressure.
Eustachian Tube Problems At A Glance
The Eustachian tube connects the middle ear space to the back of the nose.
Normally, the Eustachian tube is closed.
Partial or complete blockage of the Eustachian tube can cause popping, clicking, and ear fullness.
The Eustachian tube can become blocked from common colds or allergies.
Altitude changes can cause symptoms in persons with Eustachian tube problems.
Several maneuvers can be done to improve Eustachian tube function.
constant headache, dizziness, motion sickness, nausea, sinus pain - 
