Thanks for your question on Health Care Magic.
I can understand your concern.
By your history and description, in my opinion, you are mostly having mild irritation and inflammation in lungs due to inhalation of grass.
Grass is irritant in nature and on inhalation can cause
bronchitis.
So this can give rise to sensation of burning.
Best treatment is avoidance of grass and inhalation of fresh air.
But if you still feel uneasy after 24 hours then
consult doctor. You may need anti inflammatory, antihistamines drugs and inhaled
bronchodilator.
No need to worry for this. You will mostly improve by inhaling fresh air.
Hope I have solved your query.
I will be happy to help you further. Wish you good health. Thanks.