My child just had fresh bright red stool. He is not constipated and no diarrhoea. No other symptoms are there, didn't eat beetroot also, help?

Bloody stool. How old is he? You say he has no other symptoms, just non painful blood in stool. You should have him see his pediatrician asap. Is it bright red? That could indicate intussusception, colitis, etc. If it is darker maroon or black, that indicates a problem higher up in the GI tract. If you have a stool specimen to bring to the pediatrician, that would help with guiding him/her in the workup.