Had something similiar, however I was in a great deal of pain peeing. Doc told me it was the worst UTI he had seen and I was stupid for not seeing him two weeks earlier. The pot was practically the colour of vimto.
Slightly unrelated but relevant…once forgot eating beetroot, did a no.2 (not in the basin) only to think my insides had fallen out through some kind of horrific bowel cancer.
It took my wife 10 mins to calm me down before we both realised what had caused it.