Yes, acute HIV infection can start within three days. However, shooting pain and diarrhea can be due to viral or
bacterial gastroenteritis or stomach flu as well. I suggest, you get stool examined for infection. Take an OTC lactobacillus preparation (probiotics) and yoghurt with your meals, after giving the stool sample for examination Drink plenty of fluids (clear soups, water, ORS in water, lemonade).