Hi thanks for asking question in HCM.
The flu infection can lead to headache, generalised bodyache ,
sore throat and vomitting ,diarrhea sometimes.
Here you might have simple
muscular pain over stomach area because of flu.
Otherwise pain may be because of
gastritis secondary to viral infection.
For pain relief take simple
analgesic.If pain continues and gastritis suspected then
omeprazole is taken for few days.
I dont think here much for worry about that.Just try to get recover from flu with more water,green vegetables,fruits etc.
Avoid spicy food.
As soon as flu over, pain will mostly subside.
I hope my suggestion will help you.
If still no benefit then further work up done.thanks