Should I use Ultibro Breezhaler or Symbicort inhaler?

I am a 53 years old female. I was infected COVID two years ago and since then I have Long Covid with shortness of breath. The doctor prescribed me Symbicort 160/4.5 and it worked OK. In January 2024, I went back to North China (very cold area) and got my symptoms flared up. The doctor then did a lung function test and it showed up: Mild Obstructive Ventilatory Disorder; Small Airway Dysfunction; Bronchial Dilation Test Negative.

It seems some dysfunction is not reversible. The doctor prescribed Ultibro Breezhaler for one month and Theophylline for 15 days. However, I went to see a pulmonologist yesterday when I came back to USA and he said it was wrong to use Lama/Laba and changed me back to Symbicort. He also mentioned to not use Theophylline since its toxicity.

Should I finish my current medication or just stop it? Dose Lama/Laba work for obstructive lung disease?

Thanks!