In December 2013 I started taking Prozac for severe anxiety. I started off on 20 and went up to 40 in 3 weeks. It worked wonders for me I think or it might of been placebo, I'm not sure. I used to be able to not go out or do anything but then I just felt I could and I did and I started progressing more and more and my anxiety was slowly disappearing. Until August 2014. I went out for a meal and got food poisoning. I was sick which is the worst thing that could happen to me because I have a massive fear of it. From then on I could just feel myself going down hill all the time until the point where I felt like Prozac wasn't working anymore. I swapped to Sertraline in March 2015. Didn't last long on it because I felt it had side effects. I don't know if it did or not or if my anxiety was making me thinking it did. So I swapped back to Prozac to see if there was any change... Which there wasn't. I then swapped to Citalopram in October 2015. Felt great straight away, most likely placebo I guess. Then it kind of died down and just stayed the same. I upped it to 40 but the side effects were too bad so I had to lower it. It's felt the same ever since so I went to my doctor and asked if there was any other Drugs I could try. He told me that I would have to get them via the hospital because he's only allowed to distribute certain ones. So I had the option of going through all of that or swapping back to a previous Drug. I decided to swap back and chose Prozac because I gained the most with that. I'm now anxious that was a bad idea. In all honesty, I have no idea if a anti depressant is working or not. I don't know what I'm meant to be looking for in a good change.

If anyone can give me advice or explain how I know whether they work or anything at all then that would be great.
I feel so alone in all of this and it's starting to get really stressful and tiring.