Health advice about my son.

hi, before I say anything I'm taking him to the Dr at 10:00 this morning. but my son has constipation issues has sonce birth he's 8 months on the 7th! hes bee. having blood in hes poop several times. but the last two days he's had really loose bowls and has had more blood I'm worried. has anybody experienced this? could you give me an idea on what's going on. like I said I'm takong him to the Dr in a hour. but I'm really worried. hewas a preemie and idk if that has something to do with it or what!