I'm having trouble breathing for the past two months. It feels like I'm not getting enough oxygen to my head or legs, and my throat feels heavy with some chest discomfort. I've also had a cold for the same duration, but it's more of a stuffed nose than a runny nose. Antibiotics didnt help much. My doctor did an ECG and X-ray, and everything came out fine. She mentioned it might be an allergy and prescribed Allegra and some acid reflux meds for ten days. I felt better but not fully recovered. I stopped the medication on May 18th and can still do an hour of exercise daily, but the cold persists. There's a post-nasal drip, and the mucus feels stuck in my throat. I'm also finding my breaths shallow, needing to take deep breaths occasionally. What should I do next?