With a nasal discharge, you might be seeing an allergic reaction or possibly an upper respiratory illness or even a foreign object in the nasal passage leading to the discharge. Usually when the discharge is clear, it is due to an allergy condition. Cloudy discharges are usually associated with foreign objects. If this is the case, Benadryl can be given to your dog, the dose is up to 2mg per pound every 8 hours.You can read about these here.http://www.sniksnak.com/doghealth/inhalants.html
Upper respiratory illnesses are frequently associated with other symptoms such as coughing and would include canine influenza, bronchitis and kennel cough. You can read about these here:
You can try and see if there is a foreign object in the nasal passage, but if you do find one, do not attempt to remove it as the nasal passages are very delicate. Your vet will need to remove any foreign object found.
Now dogs can have cracking and peeling of the nose due to getting sunburned, wind burned or dried out from your heating system. You can try putting some Vaseline on it, which will help moisturize and protect it. But there is also a condition called discord lupus that describes what you are seeing as well. GSD's have been seen with this condition. Here are links to sites with more information on discoid lupus. http://www.vetinfo.com/dencyclopedia/delupusdisc.html http://www.naturalcanine.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=TNC&Category_Code=DL http://www.upei.ca/~cidd/Diseases/immune%20disorders/lupus%20erythematosus.htm http://www.jaaha.org/cgi/content/full/40/1/29#T1
If your dog does not do well at the vet, you may want to try a mobile vet. Mobile vets are becoming more common and it is definitely great for pets that do not like the vet's office or are hard to travel with. The following site may help you locate one in your area.
Hope this helps.