I agree with the suggestions made so far, but would like to add that it might also be worth considering if your body isn't lacking food or fluids at the moment. I had experiences before, where i felt fine and then took a shower, which led to feeling uncomfortable, dizzy, stomach problems, maybe circulatory problems etc. But this only happened when i wasn't eating enough or wasn't properly hydrated. But if you don't have problems like the ones the others mentioned and if you got enough food/water today, you should be fine.
And a shower can be a real blessing when taking ethylphenidate. I always feel great after it and it also helps with the vasoconstriction (but of course, only for a short time - and when having serious proplems with too much vasoconstriction it might even be a bad idea).