If you are worried it is always better to stop the fast than take a chance with your health. If you have been active try resting. Make sure you are drinking enougth, but not too much. I may seem overly cautious, but I nearly died from hypokalimia ( low potassium) and that causes heart irregularities. All water fasters need to keep some EmergenC or other electrolyte replacement on hand in case they have problems. I do hope you are feeling better by now, but take care.