Stress can certainly build up to the point that it can counteract the effect of your medication or, on the other hand, your medication may no longer be working well for you. I am not an M.D., but I do know that psychiatrists refer to this as the "poop out factor." It's not unknown and can mean that a switch of medications might be a consideration.
However, since you indicate that your job is causing so much stress over the past month or so, this is a logical place to look for the resolution of these newly returned panic attacks. You are obviously going through a difficult time and it is beginning to take hold and manifests in the form of panic. So what can you do?
One thing that you will need to consider is lifestyle changes and by that I mean that you need to get adequate sleep, some regular, mild exercise (see our Tips column for simple exercises), eat a well-balanced diet and get out for some fun with family and friends or engage in some activity or hobby that you enjoy. All of this is necessary to keep balance in your life to counteract the stress. You may not be able to do much about the stress at work, but if you can that needs to be considered too, but there are things that you can do away from work that will bolster your ability to ward off panic.
I would also suggest that you begin to use relaxation breathing and you can find a video tutorial on this also in our Tips column. Do it on a daily, several times per day basis and do not wait until you are feeling stressed to do it. Just do it on a regular basis in order to keep stress in check. Remember, stress builds up and when it reaches the tipping point you begin to get these symptoms. Some people not only experience panic but they note a skipped pulse beat which can be quite shocking to anyone. It's a signal to you that your body is giving you in order to help you make some changes.
You might also consider working with a cognitive psychologist on these work related stress issues. I do hope that what I have suggested may be helpful to you and that you feel better very soon. I also have a page on Stress at my website. The link to my website is my name below.
Dr. Farrell