When colitis symptoms appear, whetehr for the first time or in relation to a flare up, you should never, and that means never, think of waiting a few days before making an appointment to see the doctor.
The thought “I will just stay here and carry on as usual” is loaded with danger. The danger that colitis will quietly and stealthily gain control until the full force of symptoms are unleased. Then it will be case of playing catch up with the medication.
Never delay. Go and see the doctor and start the medication to defend yourself against the ferocity that colitis symptoms can throw at you.