Nose often feels blocked, esp on left side. when i look in it i see two big swollen 'lumps' in my left nostril that look quite red. what is this?

Nasal obstruction : You could have a variety of problems affecting your breathing through your nose. The 2 red lumps could be the inferior and middle turbinates, polyps in the nose, or other lesions. You also may have a deviated septum affecting breathing on the left side. See an ENT for exam and recommendations. You can be helped with this and should breathe better soon.