Welcome to the forum
@Mezz .
There are many causes, single or combined, which can trigger or aggravate tinnitus including but not limited to drug side-effects from ototoxic drugs, ear wax build-up, ear-wax removal suction, inner ear infection, Eustachian tube disorder or ETD, ear drum injury, fluid build-up in ears feeling pressured or fullness, sinus infection & congestion especially with a bad cold, TMJ, TTTS, autoimmune disorders such as Lyme Disease & Fibromyalgia, high blood pressure or blood circulation problem, anemia, loud noise exposure or acoustic trauma/shock, head injury or TBI, neck injury or muscle problems, hearing loss from aging or other causes, Meniere's Decease, barotrauma from rapid pressure changes in flights or diving, especially with congested nose or sinus causing failure to balance the pressure changes, slapping of the ears, deep grief, untreated sleep apnea, extreme/extended stress, anxiety & panic disorder, depression, sleep deprivation, etc.
T can also be caused or made worse by unhealthy diet such as too much salt, sugar, caffeine, MSG, alcohol etc. or by lacking some mineral or vitamin supplements, such as Magnesium, Zinc, B12, D3 etc.
Hope you will find the cause of the sudden spike. Good luck with your ENT consultation. God bless.