Good morning to you both!
I've gone through this stage and truthfully, it differs from relationship to relationship. The two of you are a little better off than me at the moment. Me and my SO are currently on a 'break' because he needs time to fix himself.
In the beginning of our break, I would text my SO every other day and he'd be extremely unresponsive. He also has no social media presence so I wouldn't know what was going on. If you're really really worried or concerned about him, give him a call. Keep the conversation short and light. If more than a week goes by without any acknowledgement from him, I'd call him.
We also had a talk about how he sometimes just needs a couple of days to just be alone. So we've sort of developed a system, (yes, this will sound stupid) he now has fb messenger and he'll sign on each day so I can see that he was active. This eases my mind and stops me from texting him all the time to see if he's okay and it also takes the burden and pressure off of him having to respond to me all the time. It sounds dumb but it's been working. I can go through a whole week without reaching out now.
It also seems the more space or time I give him, the more he's the one open to imitating conversation. He's been the one that has contacted me for the past 2 weeks. When it comes to making plans, I'm thankful my guy usually responds quickly. Or he does the follow up when the date of whatever it is we're doing is coming up.
This sucks to hear but sometimes they just need some time alone and apart from a relationship. It's not you, it's the ptsd.
Keep on pushing! Hugs to you both.