I started a job on Monday and I got fired today the hours I worked was 11am-8pm an the reason I got fired is because in total I was in the toilet for an hour the whole day because I'm on and when you have to change you have to change, I never got no warnings they just fired me on the spot, what can I do about it?

This is just what I would do being me but I would wright a letter explaining why it happened, that you were not informed of any rule concerning this and if need be ask for a doctors note. (doctors note- if need really be... )
P.S sorry about spellin quite ****!
Hope this helps! :)

Most employees are considered "at will employees" and this means that you can be fired for no reason at all. You can do very little if you already explained your situation. They can terminate you for being in the bathroom too much or for nothing at all.