you need not worry about it.
our bowel habit eg.stool frequency,consistency may change as normal variation.
as we change our food many a times subconciously.
beside that it also depends upon mental status.
so it can change.no problem.
at your age colon cancer
if you are feeling strain at stool then take 2-3 table spoon of isphagula husk with a glass of water before going to bed for 2weeks.
sleep with no anxiousness.
wish you a nice sleep.