This is normal, it's because you are more aware now of what was always there, the incessant neurosis of the mind, suffering etc., when the mind gets a taste of the calmness of meditation it becomes more aware of the noise so to speak. Also the mind can be like a rubber band, if you try too hard or are too tense with meditation sessions the mind can snap back like a rubber band in post meditation, being more relaxed and gentle with med sessions may help if that's the case, or maybe shorter sessions, getting properly relaxed before a session.
I've struggled with anxiety before, it really sucks and isn't easy. Aside from certain herbs, burning Tibetan incense helped me because it's medicinal, tons of brands and they are all relaxing and many are specially formulated for stress, I use Red Crystal. Try focusing on the anxiety, feel it out, what the hell is it and where the hell does it come from, where does it abide, try relating to it as an energy without the emotional and mental aspects and just be with it and mix that with the view. Meditate on the emptiness of the aggregates, the emptiness of self and the anxiety. In post meditation try focusing on the soles of your feet contacting the ground when you walk and try to remain as present and mindful as possible, when the mind starts freaking out try to stay focused on just whatever you are doing and try not to follow the thoughts. Try to keep the recollection of the calmness you feel in meditation in your mind during post meditation like a glowing ember from a fire and use that as a basis, a reference point, if that gives some feeling of soothing then it will help, like a comfort zone, focus on relaxing and let everything melt into that ocean, like snowflakes on the sea.
The nonexistence of the transcendence of suffering
is what the protector of the world has taught as the transcendence
Knots tied on space
are untied by space itself.
May I never be seperated from perfect masters in all lives,
and delightfully experiencing the magnificent dharma,
completing all qualities of the stages of the paths
may I quickly attain the state of Vajradhara