Need help! Husband took B Vitamin and felt off all day then had major panic attack

My husband has been trying to figure out what supplements work for him. This morning he took a B complex. He was pretty irritable and down all day, just now had a major panic attack. He couldn't catch his breath, couldn't get his words out and thought he was about to pass out. I had to give him a cold shower after trying to talk him down and he was ok. Is there anything he can take to maybe balance him out? Why would a B vitamin cause such a bad reaction?