Sorry to hear about the panic.
Something like EFT might help.
It has helped many people with phobias, traumatic memories, anxiety, etc.
As much as you fear the process, it is important to rid yourself of something harming you.
Some look at the 'toilet bowl' scenario as another victory battle in the war against the invaders.
Looking at it from that point of view might help.
And of course just not looking could help. (some can't resist
because of the 'ha - gotcha you little critters feeling!)
You want to start taking more control over the situation instead of the situation controlling you.
That's where the humaworm will help and a method such as eft can also.
Look at each day as a small victory - you're going in the right direction.
And that can help to offset some of the negative aspects of the experience.