identification data-epigastric pain

A 60 years old malay male initially having history of epigastric pain for the past one year,reduced after taking male, and elevated when he skipped the meal.Patient refused to seek medical attention since he is tolerable with the pain,but patient realized the pain start worsen for the past few months.Patient also noted dark colour stool for the past two month.Currently,came to the emergency department with acute abdominal pain and broad like rigidity.

please interprete the chest x-ray

• present of gas underneath bilateral hemidiaphragm
• CTR:0.5
• poor lung inflation-the 5th passing the hemidiaphragm midpoint

give the possible diagnosis at this stage
perforated peptic ulcer

list the possible investigation

• endoscopy
• full blood count
• blood urea and serum electrolyte
• urease test
• ABG

p/s;all answers were provided by kak zahid,exco kebajikan