Turning to HVAC to stop allergies

My doctor told me to take a double dose of antihistamines.

This is because my allergies have been terrible for the past few months.

I am getting constant sinus infections. I have just been miserable. My allergy symptoms did improve once I doubled the dose of the antihistamines. However, I started getting extremely tired all of the time. It was hard to keep my eyes open at work. All I wanted to do was sleep. Now my doctor is saying that the antihistamines are to blame. Even if they are “non-drowsy” they still can mess with your ability to stay away. Especially if you take 2 every day. So now I’m back down to 1 antihistamine per day and I’m less tired. But my allergy symptoms are also returning. I have decided to try to get to the root of my allergies. I got an air filter for my home with a strong MERV rating. I also got a few portable HEPA filters and placed them throughout the house. Then I read about ductwork cleaning. Apparently you are supposed to get your HVAC ductwork cleaned out every other year. I have never gotten my HVAC ductwork cleaned out. I wonder if that could be a cause for my allergy symptoms? I guess it could be so I have already set up an appointment to have HVAC technicians come out and clean my HVAC ductwork. I hope all of that works and that I start feeling better without a ton of antihistamines. I’m getting sick and tired of being sick and tired.
Electric heat pump