11year old german shepard. on glucosamine/condrotin for few years and worked. giving double dose tablets now, not working anymore, and wondering if there is something else? will contact vet for pain relief if any, but they will want me to bring him in. anyone with similar experience? my best friend and still tries to travel with me and would like to have his final months with less pain. heard of naxoprophen/etc . thanks for any info