Few question first,
How old are you, if I may ask.. age can determine sometimes the causality of Sx,
Did you notice any recent change in your stool color, to black for instance... black means that there is an upper source of bleeding like a stomach ulcer... which is consistent with the stomach cramp that you have. Or it could be a clue to more serious lesions depending on age
Where do you locate your stomach ache? Although it sounds a stupid question but people sometimes point to different places when referring to stomach ache... is it upper belly or lower belly; left or right.
Does anything increase or decrease you pain? Eating certain types of food for instance
Do u get relief by defecating? Which could indicate IBD
Do u have any diarrhea or constipation? Diarrhea or constipation can cause hemorroides or anal fissures which are a very predominant cause of bright blood per rectum. And it's is usually associated with IBD
Do u have any recent stress in your life? It could trigger IBD...
Did you loose weight unintentionally recently? This is an alarming sign sometimes...
Now for your symptoms it could be Irritable bowel disease, but usually it's not associated with bright blood unless if you have hemorrhoids, fissures or other GI tract lesions with it.
Although it might be a simple problem, I advice you to visit your doctor again and seek more help
Here's a link to an article about IBD by The American College of Gastroenterology:
Irritable Bowel Syndrome - Patients - American College of Gastroenterology
Regards,