You have a lot of problems it seems but most of it is due to your allegy. Runny nose blockage and severe headache
as also itching over the body is a common manifestation of allergy
You can start tablet montair-lc
10 mg daily at night for 10 days and things should be better. For stomach pain and loose motions eat more of leafy vegetables and more fluids.
See an allergy specialist for further help