Was the cereal prepared in breast milk or other milk (like from a cow, goat, or sheep)? The proximity of the reaction (almost immediate) suggests the possibility of a sensitivity (e.g., allergic) response, which could be to the milk or the cereal, but that wouldn't explain why she continues to have a fever after 4 days.
If you used animal milk, was it boiled or pasteurized? If not, there's a possibility of Listeriosis, which is a serious bacterial infection, and which could account for the high fever, watery stool, and pain. Other bacterial infections such as E. coli and cholera could account for these symptoms, as could a viral infection, such as norovirus. Even though a viral infection is usually less worrisome, you still need to be concerned about your baby becoming dehydrated -- make sure you nurse her frequently.
Are there other symptoms, like rapid breathing or rapid heart rate? Is she urinating normally (wetting 6 - 8 diapers a day at this age)? Rapid breathing, heart rate, and decreased or lack of urination can be signs of sepsis, and other signs can include bloating in her arms and legs and possibly a purplish rash or blackening of the skin. Again, this is serious and requires immediate medical attention. How is her body tone, state of alertness, and wakefulness? If she's limp, seems lethargic or less alert when awake than normal, these can be other signs of concern.
You say you're in Pakistan, but your question is posted from Beverly Hills, which is a little confusing. If you're in BH, take your daughter to UCLA or Children's Hospital ASAP. If you're in Pakistan, take her to the nearest modern hospital you can find. She needs to be diagnosed by a trained doctor who actually sees her. There's no way a bunch of untrained mothers can diagnose your daughter accurately. Even if someone with a medical degree were to read your question, there's no way they would offer a diagnosis without a lot more information and actually seeing your child. If a doctor determines that her stools look abnormal, culturing a stool sample may help to diagnose the problem.
Good luck -- I hope everything turns out OK.