Intermittabt fasting issues

[Hel66]

Hi, Have been managing mild ibs (D) symptoms well over the years by alleviating gluten, eating low fodmap foods and generally trying to be careful. I have low thyroid and am taking iron and vit D supplements.

Have found weight gain difficult to budge so started 5:2 diet last week fasting (500 cals) on 2 days. Since then I've had D every day. Any one know why this has happened (don't have a bug) and what I can do about it? Ride it out and continue the 5:2 or stop?

Thanks in advance