IBS flare, anxiety and an event tommorrow

Hello, I'm a long time lurker but never posted..until now.

I (F26) have been diagnosed with IBS - M when I was 14. Since I was 6 I have had agoraphobia with panic attacks, depression and anxiety but I'm ok now. I fought like hell but I won. After literaly a lifetime of panic attacks I have developed IBS. I tried every medicine under the sun but nothing worked except antidepressants (which I had to take for IBS, the panic attacks I've managed without ssris..go figure). I've been on Paroxetine for 11 years and it stopped working for my ibs, so Dr. switched me to Zoloft and it's better now but I'm still getting used to the change. Tommorrow I have a big event and today is hell. How do you guys manage this feeling before the event? Every time I even think about the thing I need to go to the toilet. And I know most of it is my head but stil.. I get that I'm venting but still I'd love to hear how are you all dealing with this awful illness.

PS English isn't my first language, sorry for any mistakes.