It seems that you have become allergic to a local tree/grass pollen that manifests as allergy whenever you visit Kerala.
Winolap is olopatadine
(I hope) eye drops that has very minimal systemic (if not none) effects on allergies.
You will need either skin prick testing to aeroallergens or specific IgE blood test
to find out what you are allergic to.
Long acting antihistamines such as cetirizine
up to twice daily is required for the season (ideally 1 month pre-season) for these to work.
Olopatadine eye drops can be used for the same duration, and is very safe.
Do NOT take recourse to oral or intramuscular steroids
I hope that was useful.