Hi.
I've gone through your query and I can understand your anxiety.
Stomach flu or
viral gastroenteritis causes nausea, vomiting, diarrhea,
abdominal pain, muscle aches, back ache, headache,fever etc.
Diarrhea and lower back pain are common presentations in case of
celiac disease,
Inflammatory bowel disease, kidney infections &
diverticulosis.
Loss of electrolytes from dehydration caused by diarrhea can result in muscle spasm & back pain.This shows muscles are deprived of electrolytes such as calcium, potassium, and magnesium.
In the history you've mentioned about having diarrhea for 5days, which is to be noted.
I advice you to take enough supplements to restore all the depleted stores.
Hope I have answered your query. Let me know if I can assist you further. Take care.
Regards,
Dr. Yogapriya V, General and family physician.