Well yes due to the surgeries and being off balance. Now i do spinning and i I can hold onto handlebars. Yoga helps a lot

Keep looking for a rheumatologist that listens. You need a specialist like a rheumatologist. A regular MD might not understand it as well.

JuelsGrothman Thigpen, AS affects your ability to walk by causing inflammation in your SA joints. It makes you have a stiff gait. The back pain can make it difficult to walk on hard surface or for long distance because with gravity, your back and SA joints are trying to carry your weight.

I used to be active, used to like long walks, going to theme parks. Now I'm lucky if I can get up in the morning or make it in to the outside world

Where did you serve ? That can also be a problem to itself. A Rheumatologist like other suggested is correct. The neck becoming stiff and difficulty with movements can be from spondylitis. The back and extreme tiredness can be as well. I hate to hear your pain, it is difficult. I also started with pain and movements at age 30. I got referred due to family history of this disease. The Rheumatologist was helpful. My pain slowed down at times.

You really have to work at keeping flexible with easy movements Yoga stretches and water aerobics are great for flexibility. At home only use a pillow that doesn’t push neck out of normal position gentle stretches with neck can help , it slow going.
Military will want to keep your job as cause for back issues and may deny any push for disability claim. Depending on where you served you could check into Gulf Syndrome. Spondylitis can be accompanied by other issues , as it does weaken the immune system itself. Get bloodwork to have proof of Rheumatoid issue and the X-ray proof of change in the radiography. These steps and finding a good rheumatologist .
I really wish you well , decreased pain and newfound hope. Remember this disease can wax and wane. Enjoy the good times and use good self care