Hi there ~
Dealing with allergies is tough. Tougher even is the fact that you are very sporty and are exposed to all sorts of allergens. It would be advisable that you wait for your allergist's appointment so that he may be able to prescribe some stronger anti histamines
for your 16 year old to have a healthy, sporty and athletic life. Also please avoid the allergens as much as you can.
Take care and have a lovely day !