Hi, Welcome to Health care magic forum.
It is not the biotin
but it is the age which is the causative. Dont worry, in many people every month it may come in different days.More over you are using the same product since long, the effective ness may be decreased.
So i advise you to change the tablets for 1 or 2 months, if you want you can switch to the old product.
Take more of green leafy vegetables, pulses, sprouts,and
protein rich foods to prevent such body changes.
Wishing for a quick and complete recovery. Thank you.