The Sooner The Better
Hi Brian,
I urge you to get in to at least see your Primary Care physician right now. Please, time is of the essence here.
PTSD surfaces after untreated trauma occurs. Think of it as internalized grief and guilt. You have to get into a place where you can safely let it out and deal with it out in the open. The longer it is sealed up, the more damage it is going to do to your psyche. If it goes on long enough, it starts making permanent brain changes that are hard to undo.
I fought against taking the meds for a few years, but they really are useful to let you get to a mental place where you can grieve and let go. I know that examining these things is terrifying to you right now, but the professionals can help.
If you are only about 5 months out from the end of your tour, you have a better than good chance to intercept this path and turn it around now. The sooner you walk into a professional's office, the better. Walk in, lay it out to them, and let them help you.