Ask the doctor. Speak with the doctor who prescribed the medication. If you mean really bad when you say not too good - go to an er. Here is a loooong list of side effects to help you decide if you need fast or slow help. I wish people could be better educated about their meds - the whys? Hows? And side effects and alternatives. This may be a start for you. http://www.drugs.com/sfx/propranolol-side-effects.html.
Not unique. Propranolol is a beta blocker, and has numerous nasty side effects, including asthma, depression, fatigue, exercise intolerance, slowing of pulse, dropping of blood pressure, and cognitive problems (memory). I do not use this medication in any of my patients due to the adverse effects. If you need a beta blocker for cardiac issues, other newer meds have less side effects.