It's normal for allergy symptoms to vary from one day to the next (reasons are numerous). Have you tried immunotherapy (allergy shots)? My Brother has seen remarkable help for his chronic allergy symptoms.
Also, has your home or workplace ever had any flooding or do you live in an area with high humidity (most of the USA that is East of the Mississippi River has high humidity, as does parts of the Pacific Northwest)? If so, you may be reacting to mold in the air, so you may need to find a way to reduce exposure to the mold. There are companies who test for mold and repair damage caused by mold.
If you work outdoors, then you might be experiencing varying symptoms as mold and allergen air concentration levels fluctuate. You might want to wear some kind of allergy filtration mask during your most allergic season of the year (i.e., the time when your symptoms are most significant).
Great topic for discussion with your Allergist or whoever treats your Asthma. Take care,
Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication Allergies, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD (Lupus?), Osteoporosis, Anemia, Very Low Lymphocyte Counts (T-Cells & B-Cells), malabsorption/malnutrition, possible Lyme Disease (Igenex Lab IgM WesternBlot positive), etc.
Meds: Pulmicort, MaxAir, Injectable Vitamin B12, Herbs, Nutritional Supplements, Essential Oils, Homeopathy.