Welcome to XXXXXXX forum.
Let me know the exact site of pain (whether left side or right side).
There may be possibility of abdominal muscle hematoma
probably due to localized injury
Hematoma in abdominal muscles are painful in touch as it is confined to muscle sheath.
Presence of localized pain along with tenderness suggests the diagnosis.
You should consult with XXXXXXX medicine specialist/ general physician and should go for thorough check up.
You should also go for ultrasound
imaging to localize the depth of bruise
Hematoma gets resolved with time and as such there is no need of any medication.
You should take bed rest
Hope that helps.
Let me know if I can address any more concerns.
Dr. Mayank Bhargava