You mentioned you had a health check done, I assume a urinalysis was done (with 1st morning void) to rule out a bladder infection.
My older female Cassie was misdiagnosed when she started having problems "holding" herself. The test results came back fine, due to her age I came to the conclusion of incontinence. A few months of living this way she developed an infection and had to go on antibiotics...not only did her infectin dissappear...so did her urinary incontinence problem. Did I feel like a heel for letting her go that long, and I kick myself for not taking in another urine sample (first void - very important). This was back in the day before I knew about homeopathic remedies and herbal support.
When my male started having "accidents" I had him tested twice before I found out he was suffering a bladder infection. I think my Vet needs new equipment
. I used homeopathic remedies to solve his problem. He developed this problem after he was nuetered at 4 years of age...never had a problem when he was intact...so, I assume it had something to do with an adverse reaction to the surgery.
If your sure it's not health related, I would then take a look at the whole situation. You dog may be comfortable, but, does he relax when you leave? What you could do if you don't already is: leave music on, or TV so your dog has human noise in the background. Give your dog rescue remedy or other calming herbs like chamomile or valerian root to help take the edge off the stress of your leaving.
Make sure that you never punish a dog for house soiling. If you catch your dog in the act take the dog immediately outside and then praise for going in the "proper" spot. If on the other hand you come home, find a "mistake" and get upset, your dog is now assoiciating you with being unpredictable and scary which in turn will make the situation worse. Most dogs that suffer from aniexty attacks usually do the worst damage about an hour or less before the owner comes home. The aniexty of not knowing what mood the owner is going to be in when they come in the door can stress some dogs out. A negetive reaction can be as small as negative facial expressions, a stern tone of voice, remain calm and nonthreatening.
For some homeopathy remedies you could try Aconite for incontinence associated with fear or anxiety or Staphysagria may help an emotionally sensitive dog who is mortified at the slightest correction.
I have used vinegar and water to clean up areas. vinegar seems to neutralize the scent of urine. Some dogs will continue to go in the same place if they can smell their scent.
As already suggested keep your dog contained to one room, like the kitchen. If you feel your dog has a hard time holding his bladder, maybe you could litter train him. Provide a diet with fresh foods and plenty of variety for urinary tract health. Make sure you supplement with omega-3 fatty acids. If your dog is suffering from stress (seperation anxiety) supplement the diet with B-complex and antioxidant blend.
If the problem persists; avoid dry kibbles in favor of wet foods and homemade diets. Feed raw fruits and vegetables - tofu, bulgur and yogurt, broccoli, millet, cod, spinach. In rare cases urinary problems may be caused by an allergy.
For herbal support:
astragalus -supports the immune system if an infection is present; also helpful as a general tonic.
Chamomile and marshmallow work together to soothe and promote healing in the lining of the urinary tract.
Cornsilk fresh from the produce department is an excellent remedy for any chronic inflammation in the urinary tract.
Cranberry or blueberry prevents adherence of bacteria to the lining of the urinary tract.
Dandelion- good tonic for the urinary tract.
Good luck