I am not sure you understood what takes place, when they stabilize the pressure there is no danger. The danger is in the ascent and in the descent when you have to correctly pop your ears as many times needed. If you don't, they start to hurt. And you may get a barotrauma. Did you pop your ears open every time you felt them stuffed? This is what you really have to do. There are several methods to do so, swallowing is one of them and I thing it is better than just chewing.
They have doctors there, they can examine you to see if you suffered a barotrauma. They will tell you to continue or not. Although I don't know how a barotrauma feels, or what exactly it does to your ear, I think it can heal.
But I don't think you suffered a barotrauma and I don't think your Tinnitus got worse by the HBO chamber. My Tinnitus is constantly fluctuating, there are good and bad days, usually cold days are bad for example. I think that HBO did not affect your T in any way. I give it little chance to help you, perhaps if you went the first couple of days after your acoustic trauma it would.
I think it is a placebo feeling. I did have placebo feelings during my sessions too. When the session was over, I felt my T was less loud. But during the day, it was coming back to its regular state, unfortunately.
Now if you are certain your T got worse, then don't continue. There are several people in here that thought after the 8th session the got better, they continued and then after the 15th session they got worse. And they regretted continuing. This is all placebo feeling according to my experience. I did feel a bit better at the beginning, but is was not real. Or it was a temporary feeling. The HBO chamber did nothing to my tinnitus. I did get to it a bit late, 2 months after my acoustic trauma. Perhaps an earlier treatment would give results, perhaps not. Nobody knows. They say that they have good results the first month. And less good results in the second and third. Then the results get really poor. In my opinion, in acoustic trauma cases, one has to act really fast and in the first couple of days do what needs to be done. Not much really, corticosteroids (have you tried?), some blood circulation drugs and perhaps start HBO therapy. Still, it does not mean he will heal, perhaps nothing will be done even then. Nothing can be proved, these are just what specialized doctors say. In my opinion, the first two days are the days that an organism may heal by itself. How can it be proved that one is healed because for example took corticosteroids? But since it is the only treatment there is, and perhaps HBO therapy, one should try them ASAP!
Now I am not saying you are too late, you should try everything there is and maybe get lucky.
If you don't, you will just wait like all of us older patients, for a new treatment.