The antibiotic that your dog has been taking for the anal gland infection, Trimethoprim sulfa can cause a condition called Dry Eye (Keratoconjunctivitis sicca, aka - KCS) in certain dogs. The medication has the effect of decreasing tear production and the eye could look bulgy, but, it would also look cloudy and irritated. This problem can reverse itself once this antibiotic is discontinued, but sometimes the problem is permanent. There is a very effective treatment for Dry Eye, even if it permanent. German Shepherds usually don't have this problem, with this antibiotic, and it is uncommon even in the breeds predisposed to developing it, therefore, it is unlikely but still a possibility.
Older dogs eyes tend to begin to look like they bulge due to aging. The cornea's in older dogs look cloudy and slighly bluish due to nuclear sclerosis or lenticular degeneration, which are just benign aging changes, and usually do not affect the dog's vision very much, but these changes are very gradual and don't show up suddenly in one weeks time.
Dog's eye's can also bulge due to glucoma, which in your dog was not the case, luckily. Another cause is a tumor behind the eyes that pushes the globe's out, however these tumors are rarely symmetrical, in that both eyes usually do not bulge equally.
Anaplasmosis infection could make your dog weak and sometimes anemic and should be treated with doxycycline.
If your vet is unable to sort this out, I would ask your vet for a referral to veterinary opthamologist. Good Luck!