My hisband had his second hep b vaccine today and now he is experiencing the following symptoms drowsiness, nausea, difficulty breathing and his arm and legs feel heavy. should i be worried?

Allergic reaction?: He needs to be seen immediately by a doctor or clinic, especially if the symptoms -- particularly the breathing problem -- began within an hour of vaccination. Allergic reactions to HBV vaccine are rare but can happen.

Emergency : Please proceed to the Emergency room.,He may be experiencing an acute illness, cardio pulmonary condition or an allergic reaction.

Unfortunately yes: The most concerning of these is the difficulty breathing so I hope you have already followed the advice of my colleagues to seek urgent care. Like all vaccines there is a potential for serious side effects. Based upon this I recommend your husband not get any further Hep B vaccines. See https://www.nvic.org/vaccines-and-diseases/hepatitis-b/vaccine-injury.aspx