This is an interesting suggestion, as obstructive sleep apnea
being linked to PTSD is not a common connection. Usually, PTSD is related to stressful events that have happened in the past. Two tours of duty are a likely source of this stress (and, on behalf of others, we thank you for your service!). While this can create many issues in the rest of your life, it would not usually be directly related to sleep apnea, at least the obstructive variant, so you should definitely speak with your doctor
about what may be causing this. Obstructive sleep apnea is usually caused by excessive soft tissues of the upper airway obstructing the airway while you sleep. As the muscles of the airway relax during sleep, the soft tissue falls into the airway and blocks it. This leads to a decrease in oxygenation, which causes the brain to wake the body up briefly to breathe. With increased muscle tone that comes with awakening, the air goes in and out of the lungs readily, fixing the problem. Typically, this problem is completely anatomic rather than mental. Fixing this problem comes either with a machine that puts pressure into the airway to splint, or hold open the soft tissue (like a BiPAP machine), or by surgically debulking some of the tissue. Please speak to your doctor about potential corrections, and perhaps visit an ENT surgeon
for more options. I hope you're feeling better soon, and good luck!