What could be wrong with my stomach? Been takin oxycodone 30 mg for 5 years now having horrible constant pain in lower mid side of lower abdomen very painful if u push on it

See your Doc. There are many causes, some related and most unrelated to your chronic opioid use. You definitely need a doctor to examine you.
If . If you are having severe constant pain then you need to be medically evaluated. The oxycodone in itself would not cause any severe abdominal problems (other than constipation), but it could mask symptoms of a more serious problem. Any abdominal pain is a concern. If you develop fever, increased pain, or vomiting then you would need to be seen immediately.