Hi.
Thanks for your query.
Noted the history and understood the concerns.
Combination of
vertigo, runny nose, fever with chills and heaviness at the back of head can be due to upper
respiratory tract infection,
sinusitis causing infection to travel to the
inner ear causing vertigo, headache and all the symptoms you have mentioned.
The sick stomach can be due to the ingestion of the infected secretions from the upper respiratory tract.
I would advise you the following in such a situation:
Get an opinion of an ENT Surgeon, clinical evaluation, ENT
Endoscopy, relevant tests of ENT, blood, urine and stool.
Get nasal and oral decongestant, antibiotics, anti-inflammatory medications, steam inhalations, rest to get a relief and cure.
If the vertigo returns, you will need medications for that too.
The antibiotics should help you for stomach problem too. You can add on a PPI and antacids as these conditions can raise acidity and related problems.