Had an Episode last year questioning reality, I got past it. Now it's starting again, what's going on?

About seven months ago out the blue I had a mental breakdown. I've always been anxious but nothing like this had happened. I got a daft thought into my brain after one day of drinking about what if this isn't real, this reality isn't real. It got worse and worse over two weeks and I couldn't shake the thought of it. I had a total breakdown and to skip on all the details it was an extremely stressful time to say the least. Wondering how I could end this thought pattern, I knew it was silly but my brain wouldn't let it go.

After eventually getting past it I started taking Sertraline from my GP, started at 50mg and now on 150mg. Also I'm temporarily on Zopiclone as I've always had insomnia for years and only get about 3-4 broken sleep each night.

On top of that I also have tinnitus in one ear which has recently gotten worse not long after my episode and that causes me great anxiety. I have OCD when it comes to dwelling on thoughts which is what happened during my breakdown and for checking locks and things but I'm fine when it comes to germs and things of that nature.

Now since that episode I've never went back to that place in my mind and I don't know if the sertraline is doing anything but I presume its helping. I've been able to talk about what happened and did see a psychiatrist after four months of waiting, but she was at the lowest level of care and had no idea how to discuss my problem.

Now randomly last week the thought crossed my mind again which I've been able to shake since that episode and recovering but now I'm starting to question reality again. I'm aware it's silly thought but my brain keeps popping it into my head, which makes me anxious on top of my general anxiety on top of my insomnia and tinnitus and its all going round and round at the moment.

I do have a review of my medication in April and I'm also being re-referred to the next level psychiatrist. But does anyone have insight or reassurances they can offer.