Looks like you have a throat infection- which causes pain while swallowing, fever
It may be viral or bacterial.
If you have infection in your sinuses
too, you can have head ache.
Your tummy ache might be due to gastritis- which might be due to infection as such or ibuprofen
My suggestion is, please have yourself seen by a doctor. Your doctor will examine your throat, sinuses, chest etc and will give you antibiotics if needed and other medications like antihistamines.
Do not self medicate.
Hope my answer helps you.
Wish you a speedy recovery.