my 2 year old son do the poop in 2 days or 3 day normally but since last 5_6 days he was going for 3-4 times and i took it normal as the result of antibiotics he has taken for fever and cold and cough last week

But today his stool has some traces of blood (seen 2 times till nw since morning) which is not constipation as he is pooping. 3-4times...so now i am getting tensed that what could be the reason?? can somebody suggest anything??