Yes - it could definitely be Valley Fever. Here in Arizona, especially, it is not uncommon. I often pet-sit for a friend whose elderly black Cocker Spaniel has had Valley Fever. Joint aches and pains, a persistent cough, listlessness, lack of appetite, lots of sleeping are some signs but a lab test is needed to confirm. Otherwise, also for consideration is possible hip dysplasia, for which some breeds have a genetic predisposition (e.g., German Shepherds, collies, and usually other large breeds). In this condition, the rounded head of the long leg bone (femur)shifts out of position from within the hip socket...goes "out of joint." This can be due to laxity in the ligaments and/or muscles, or due to some malformation in the actual joint itself. It is aggravated by the animal being overweight with more stress then being put on the joint, and can be aggravated by activity. Arthritis often occurs as well. This can be diagnosed with proper x-rays of the dog's hip area. Talk to your veterinarian or a specialist for further guidance. Good luck.