Tinnitus can be a very difficult problem, as it has many causes. I have been dealing with tinnitus treatment over the last 18 months using a specialised Low Level Laser Treatment (LLLT), which has had some success in specific patients. I have had my results of a patient study published on the internet, and I am a member of an international laser therapy group which is attempting to develop the use of laser. In this particular case, I believe that your patient is in a smaller sub group of patients that have tinnitus, at least in part, due to the cervical spine and the TMJ. I try to differentiate this group by asking patients to rotate the cervical spine and maintain the end range of movement for 20 seconds, and the same for lateral cervical flexion, noting any change in tinnitus symptoms. The patient is also asked to clench the jaw evenly left and right, then more one side then the other, plus a side to side jaw movement. Note any pitch or subjective volume changes.
Move on to palpate the cervical musculature around the TMJ, mastoid, and the scalp around the ear.
Strangely, some patients have symptom change with the slightest scalp pressure, and others have variable change dependent upon the amount of digital pressure or the area. It can be very specific.

It is my belief that an alteration of muscle, skin, or ligamentous pressure around the accoustic meatus (ear hole), changes the size / diameter of the opening, affecting the accoustics. This effect is similar to a musical wind instrument, where changing the diameter or length of a tube can alter pitch. This can also explain why patients have symptom alterations when changing altitude (driving into the hills), temperature changes or stress (increased blood flow and or pressure).
Physio techniques which increase blood flow or pressure, increase temperature, or affect tissue tensions, will alter a patients symptoms if affected by this type of tinnitus. So does muscle relaxant medication, although medication can be an issue with tinnitus, as some types cause inner ear changes.

I will not discuss the inner ear, or the central nervous system contribution to tinnitus, due to lack of time - to involved. Suffice to say that chronic tinnitus can have multiple areas implicated, and that treating one area only will only provide partial relief.
Laser treatment can only assist those with inner ear type tinnitus.

For your patient I suggest stress reduction and muscle/ soft tissue gentle prolonged stretching techniques around the TMJ, mastoid, and upper cervical spine. Spinal mobilisation techniques may be of assistance later on, but can aggravate symptoms in some cases. Be very careful or avoid spinal manipulation techniques until gentler techniques have ben assessed.
Finally, you will discover that the majority of treaters world wide (including specialists), believe that Tinnitus is untreateable, and that it may eventually burn itself out. Some figures suggest that (in the Western World, 20% of people have tinnitus at some stage in their lives, and that 20% of these can be severely affected - some to the point of becoming suicidal. The increase in portable ear bud style music players with volumes up to 130 decibels is creating a new generation of hearing problems, with testing demonstrating that some 20 year olds have test graphs similar to 60 year olds! Tinnitus can be the first sign of hearing problems developing.
Hope the above helps.
MrPhysio