If decongestants aren't recommended for you, then I'd suggest trying something called Zycam. There is one for colds and one for allergies. They are homeopathic (natural) and therefore have no side-effects or interactions with other medications. You can find the product over-the-counter in some drug stores and health food stores.
Also, I've had sinus infections and my doctor has said that they often take much longer than 1 week of antibiotics to get rid of because the sinuses are so labyrinthine and any allergies or other causes of sinus congestion (such as a cold) can make getting rid of the infection very difficult. My doctor did recommend saline nasal rinses with a netti pot (or you can get over-the-counter saline nasal spray) to help wash away the infection and keep the mucus membrane moist.
I hope this helps - take care,
Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication Allergies, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD (Lupus?), Osteoporosis, Anemia, Very Low Lymphocyte Counts (T-Cells & B-Cells), malabsorption/malnutrition, possible Lyme Disease (Igenex Lab IgM WesternBlot positive), etc.
Meds: Pulmicort, MaxAir, Injectable Vitamin B12, Herbs, Nutritional Supplements, Essential Oils, Homeopathy.