Honestly - I have PTSD and anxiety, as well as a couple other things - and yes one can trigger the other. It's referred to as a "domino effect".
I am in the same boat as you - have not had issues for several years until recently and now the things I used to use just are not. It's been so long I'm having to ask "was this an anxiety/panic attack" sometimes bc I don't always recognize the symptoms as being "definitive".
From what you describe, it sounds like you had a trigger that set off your PTSD and in turn your PTSD triggered off a panic attack. (domino effect)
As to how to prevent that particular type of thing from happening .. if you know your triggers you can avoid them, or if you know how to control your responses to them - be sure to be in tune with when you are starting to get too worked up around the thing that triggers you n remove yourself from the trigger immediately.
Once you find yourself in a PTSD episode - grounding techniques work sometimes. If you can catch yourself before you get too far into the episode sometimes you can prevent the domino effect from occurring.
If you find yourself in a panic attack - that's when you need relaxation methods or techniques.. I am not sure what you have tried so I dont know what to suggest.
For coping during the time between sessions - I would reccommend daily walks. Walking is good for many reasons. I wrote a post regarding it in the depression forum but it pertains to anxiety for the same reason.
You can read it if you like.
Some Old Advice - from the earth
Serotonin is well-known for treating depression but it is also something the body naturally produces .. and something which the body uses as an anxiety attack inhibitor, so when you read through that post - do not dismiss the information regarding serotonin, please. It will help a lot. Much love to you. ❤