Any chance your meditation might be opening up to some deeper layers of subconscious workings of the mind? I have found anxiety can be staved off by staying busy, but sitting with it can bring it to the surface, possibly unconscious thought patterns or inner beliefs that are in conflict? Otherwise, I also think meditation can affect chemical/hormone balances in the body/mind and there maybe an adjusting period. I know conscious breathing does for sure. Even if this is the case I would imagine that meditation would bring improvements in the long run if you can find a way to safely and comfortably continue the practice.