M.B.
You should do your neti pot everyday. Also, you should take probiotics since you were on antibiotics to add back healthy bacteria. It sounds crazy, but stuff in your gut can impact sinuses. One cause of sinus problems that they've recently discovered is H. Pylori and another is fungal infections. The latter makes the most sense because the antibiotics allow the fungal stuff to go to town. I almost always need anti-fungals after having been on antibiotics. You should ask your doctor about that. Fungal infections can be far worse than the sinus infections and cause the type of fatigue you mention. There are herbal/natural anti-fungals out there. One of my favorite brands is the one from Garden of Life (Fungal Defense) - it's not cheap, but it works well. Also, note that soy is another potential allergen, so you might want to switch to rice milk, until you resolve the issue. I also wouldn't entirely rule out a true dairy allergy rather than just lactose intolerance. I thought I was lactose intolerant when I was 32, only to learn 10 years later that I had a true dairy allergy.