I am sorry to hear about this concern.
Two separate issues it sounds like.
So, first for the hip issue, even if back to walking better, he clearly needs some better supportive care to manage the joint problems. So, that means some combination of joint support supplementation, definitely a trial run with a non-steroidal anti-inflammatory, and lastly, a pain medication, only if needed.
A few common medications prescribed by vets (not all options,but many of the most common choices): NSAIDS,RimadylDeramaxxMetacam
Currently, one of my favorite joint support supplements on the market is Dasuquin or Cosequin. Here is some more information about it. Many veterinarians and clients have observed that after a few months on a quality joint support product, they can often reduce the dose of the non-steroidal anti-inflammatory medications there pets may already be taking. A supplement can take several weeks to observe benefit, so it is important additional anti-inflammatory or pain medications are used in the meantime. Product Information about Dasuquin / Cosequin
Also, an incredible clinically tested food to help with joint problems is J/D. J/D Diet
Another supplement to review would be Adequan injections for joint health. These injections are also quite popular and have helped many pets with arthritic disease. Adequan injections
Now, the breathing issues. It sounds a lot like either collapsing trachea episodes or reverse sneezing fits. Some here is some extra information including some videos. The additional links also talk about therapy.
You could be describing reverse sneezing or a collapsing trachea condition:Reverse Sneezing VideoReverse Sneezing Information
.Collapsing Trachea VideoCollapsing Trachea Information
Please let me know if there is anything I did not cover for you. I hope that information has been helpful.
Please remember to select Reply to Expert, if for any reason you need further clarification, have more questions, or were expecting a different type of answer. Please, hold off providing your feedback rating until you have asked all your questions.
Otherwise, I greatly appreciate your rating to close the question. My goal is to try and provide you the best answer possible.