Hi, many thanks for the query!
Severe sharp & intermittent pain with nausea
suggests ?ureteric stone, headache can be due to fatigue
& exhaustion caused by recurrent severe abdominal pain
, bloatedness goes in favour of ?colitis
To come to an exact diagnosis- get an USG (Abdo-pelvis) done after adequate bowel preparation with your Doctor's advise & till u get your USG done, u can take symptomatic treatment as per your Doctor.
Wish u a good health. Take care.