Do you have your dog on other supplemental herbal or holistic meds or treatments as well, such as condroitin and glucosamine, as well as calcium. Of course this should always be cleared with your vet, but there may be some supplements that could help also. There are some dog foods that have this, as well as fish oil, and many other things for bone health.
He is a senior, so should be eating a senior food specifically designed for his bone problems. I am assuming this is what he is being treated for, as Tramadol is most often prescribed by vets for joint pain.
Have you also considered taking him for water therapy, or even just learning massage techniques that can help him with his pain? I know this can be very helpful, and sometimes the dosage can be lowered by doing some phyical therapy, just as it can with us. Heating pads (on low) or a "warm" hot water bottle, wrapped in a towel so there isn't a hot spot, can also ease his pain.
I sure hope the little guy gets the dosage of Tramadol adjusted, and he gets to feeling better soon. Please let us know how his vet visit goes.
Here's a link to a site about Meds for dogs.
Tramadol