Eat more and halve your current Xen intake - your body may not be reactig well to it.
Once you can use it (at half dosage) without any side-effects, you can try 3/4 dose and if that's ok take it up to the full dose.
Hopefully the extra food will sort you out, but in case your particular physiology is reacting badly to the Xen, you should reduce it to be on the safe side.