Thanks for writing your query.
can result in itchiness due to congestion. Swelling felt on left side of throat can be due to swollen tonsils as a result of infection.
Congestion can be relieved by taking antiallergic like cetrizine
10 mg once a day along with decongestants like phenyleherine or pseudoephedrine
along with antiinflammatory drugs.
Doing gargle with antiseptic solution like Betadine
Gargle two to three times a day will have added benefit.
You can have a Throat swab culture to know if any infection is present and can start antibiotic according to the report of the culture.
and spicy foods.
I hope this is helpful to you.