My six yr. old has blood and mucus in stool?!

My six yr. old has blood and mucus in stool?

My six year old son threw up once last night, and had some stomache pains. Today he's been fine. Except once this afternoon he passed gas and there was mucus and blood in his underwear. I took him to the doctor, but there wasn't enough there for a culture. Now, he's done this twice (passing gas),with more mucus/blood,since we've been home. The doctor said if there's any clots go to the hospital. If not, take a stool sample to the office in the morning. Any ideas what could be wrong?Thers no tears or hemmoroids down there. He's not on medicane, and nothing has been changed with his diet, etc. I'm just worried until the next visit tomorrow.

My son had the same thing , when he was only 18 months old and they found out it was salmonella poisoning. They have to wait on the lab report, but if that's what it is , it can be caused by some chicken , he ate , try to think back of what he might have been eating , that you all didn't and sometimes it is, when a child is younger , they are more susceptible to things than we are , meaning that you all as a family could have been eating the same thing, but only he got sick.
Just pray for him and trust God, that He will heal him of whatever it may be.
God bless you and your son