All your symptoms are indicative for virosis complicated with gastroenteritis
(diarrhea, feeling sick).
So, first, suggest to take lots of rest.
Get plenty of fluids, water, tea.
Take tasectan for diarrhea, oral rehydration salts to stabilize the electrolytes, butylscopolamin or papaverini for pain, multivitamin
, probiotics, and start omeprazole
for 2 weeks. Most of these medications can be taken as over-the-counter with no prescription.
Wish fast recovery.