Acute and Chronic Sinusitis

Symptons and signs:
Upper Respiratory Infections (ie cough, nasal discharge, passibly fever and chills - ie 'a cold) that are accompanied by "fascial pain  (Degown & Degown' Diagnosistic Examination, Richard L. DeGowin, McGraw Hill Inc 1994)  suggests 'acute suppurative (draining) sinusitis'). If it is the maxillary sinus then the fascial pain is dull and throbbing in the cheek and several of the upper teeth on that side.  Thumb pressure tenderness may be noted over the sinus invoved. Frontal sinus involvement is noted with pain in the forehead and along the eye brow ridge.  Ethmoid sinus is medial (next to) the eye and deep feeling. Sphenoid Sinusitis generates pain behind the eye.  Chronic or subacute sinusitis is sinusitis that lasts more than 3 weeks.  Xray or CT scan may help with the diagnosis at this time.  12 week is the figure used by Mayo Clinic for diagnosis of 'chronic'.
Treatment:
Home remedies for acute sinusitis are warm compresses on the face, avoid alcohol, sleep with head up to increase drainage, antiinflamatories ie aspirin, ibuprofen, lots of liquids, antihistaminines, juices especially.
Antibiotics for empiric treatment, ie treatment where it's based on symptons and signs rather than an actual culture of the pus, include amoxil 500mg tid (three times a day) for 10 to 14 days, trimethoprim/sulfamethoxazole 1 DS tab bid (twice a day) for 10-14 days, cefuroxime 250 mg po q 12 h for 10 to 14 days, clarithromycin 250 to 500 mg twice a day for 10 to 14 days, azithromycin 500 mg for 1 day then 250 mg per day for 4 days......(Epocrates)
For Chronic Sinusitis Empiric Antibiotic Treatment changes to include Clindamycin 450 mg 4x a day for 4 to 6 weeks and metronidazole 500 mg twice a day for 4 to 6 weeks followed by a macrolide treatment for 4 to 6 weeks or amoxicillin/clavulanate 875/125 mg twice a day for 4 to 6 weeks. The last one, Amoxicillin/clavulanate may interestingly be used for acute sinusitis as well and is the only one which could be recommended for both.  (Epocrates).
Always with antibiotics avoid where person is allergic.  Note each antibioltic has side effects and those side effects will often make one better than another for an individual patient.
For this reason it's obvious that seeing a physician is the best medicine.  Ear Nose and Throat surgeons are the people who are the specialists and authorities on this condition.  They have little cameras on probes which they can use to enter and look in sinuses and extract fluid for culture and sensitivity assessment of antibiotic optimization.
Sinusitis can be caused by fungus.  It can be caused by allergies. It can represent an underlying autoimmune disorders. All infections can be made worse or arise in depression and stress. People who are over stressed or experiencing anxiety and depression have reduced immunity and risk for infections and risk for persisting infection is increased.  Rest is therefore beneficial at first.
Psychosomatic medicine suggests that people who are healthy are best able to fight illness however those who are chronically stressed, threatened, abused, neglected, over tired have less 'fight' in them. They are more at risk for having a mild illness become more major or extended. Why if a 'bug' is equal, do only certain people in contact with that 'bug' get infected.  That's what immunity is about. Some people are more immunity. Immunity is affected by stress.  Mind and heart affect immunity.
Environmental factors such as cold and damp are not conducive to sinus healing.
Sleep disorders increase risk of infections because sleep is a time of self healing. Pain disorders beget sleep disorders and sleep disorders beget reduced immunity to psychiatric and physical illness.  Too often we treat connected matters as disconnected when in fact they aren't.  Today most things are recognised as multifactorial.
However, often a 'cure' can result from a change in a specific or focal area: resolve the pain or improve the sleep, and the immune system can take care of the sinusitis.  Sinusitis affects sleep by affecting breathing and thereby can cause depression and pain is worse with depression.  So there are these inherrent cycles that can work against one unless recognised. Then the very cycles can be used to benefit the individual.
Using an antihistamine to improve breathing and drainage from sinuses can improve sleep and thereby improve healing.  Advil sinus is one of many over the counter preparations which can be used early.  While it is considered messy, the old fashioned sinus washing process is actually still considered beneficial and recommended by some ENT specialists.

MayoClinic.com is a good safe mainstream resource.