May be Gastroenteritis
Thanks for your query.
Noted all the history and understood your concerns.
One week is a long time to have pain in abdomen and now shaking. You also have a feeling to throw up and headache too.
The most probable cause is gastroenteritis.
Hence I would advise you to the following:
Insist for stool and blood tests as it helps whether there is any intestinal infection and if present needs a proper antibiotic cover with symptomatic treatment for pains, headache and nausea
With the medical history and current medications, you need to be bit extra careful and watch for any other symptoms like blood in stool
, black stools and so on.
Till then you can have plenty of oral fluids, take rest and electrolyte solutions if you are feeling tired.
I hope this answer helps you.
Please give feedback after your visit with a Doctor and details about the reports and advise.