Hi, Benja, and welcome! You've come to the right place for advice, support, and information about tinnitus.
The fullness you're experiencing right now is pretty common. I had that fullness feeling for quite awhile myself, but it finally went away on its own. What causes it? No one really knows, but it may have to do with an imbalance in the Eustachian tubes. As your body and brain get used to the tinnitus, you'll probably find that the fullness feeling will subside, too.
Right now, you should try to remain calm about your tinnitus. Try to find ways to distract yourself when it is at its worst. At night, you might try some soothing sounds, such as water sounds, to listen to when you're falling asleep.
Some people find that antidepressant drugs help them get through the first months of tinnitus. Others (like me) use natural supplements instead. I tried a lot of supplements when my tinnitus first started, but what worked best was magnesium (I use magnesium chloride), and for calming you could try holy basil, reishi mushroom capsules, pharma GABA, or other such supplements.
We all wish you well, and are here to offer mutual support and suggestions based on our own experiences.
Best wishes and hugs,
Karen