Thanks for posting your query.
With the available described symptoms, there could be possibility of acute viral gastroenteritis
or peptic ulcer disease
Relief in abdominal pain
after eating suggests the possibility of peptic ulcer disease.
Myalgia is an integral prodromal symptom of viral infection.
You should consult with internal medicine specialist and should go for thorough check up.
You should also go for complete blood count
, ultrasound imaging, endoscopy and serum electrolytes.
You should take complete antibiotic therapy, proton pump
inhibitors, antispasmodics, probiotics, antipyretics and muscle relaxants.
You should maintain your hydration by taking potassium rich liquids.
Avoid milk and all milk related products.
There appears to be least chances of STDs.
Dr. Mayank Bhargava