I have had a lingering cough with phlegm for over a month was on antibiotics w diagnosed sinus infection. when i wake up in the morning my chest feels a little tight and when i breath in i feel a rattle but it goes away after i have been up for bit.

Nasal inflammation: Hi, this is a common situation for a many people. Nasal inflammation/swelling from your recent sinus infection or due to allergies can produce mucus that can cause post nasal drip. Dry cough, especially at night/morning and then getting better is classic. Saline rinse/humidifier/raised pillow when sleeping/medicated nasal spray to reduce inflammation can help. Hope you get to feeling better soon