Right side of the abdomen is occupied by
liver, Gall bladder, cystic duct, right pleura and lung. Won;t suggest you do an USG or a Xray without a physical exam, it is better you do a physical exam first and then decide on investigations. Try to take a simple analgesic like paracetamol (Calpol or Crocin) to relive you if there is no allergies,
Next Steps
Come fr aphysical exam. Today is Tuesday, Might suggest a standing plain X Ray and USG abdomen
Health Tips
Eat high fiber diet, simple food, eat on time, prevent acidity, don't fast, see is there is fever or cough. All the best. Don;t worry. I am sure he will be Ok soon. Let me know his progress.