Need urgent help!?!!!?

Right here is my problem. My mare is extremely fizzy - spooky, fizzed up, jogging on the spoke, not concentrating yet on foot she would stand and sleep tied up when there was a bomb dropping 3 metres away from her, litrually! I put her on a calming powder, she had low sugar, un molles, calm and condition and that hasnt made a difference. I want to take her hunting this season, but its like she's on edge all the time. What method could I do to calm her down and make her concentrate? Or a feed? Has to be in england. Please help im so desperate to take her hunting!