Is it bad to yawn excessively I had a concussion a couple of days ago and I've been feeling really tired since, what should I do?

REST. Concussions cause fatigue and the treatment is to 'rest the brain'. 'yawning', tiredness, napping, decreased concentration, headaches are common symptoms. You should be getting frequent follow-ups to check progress. Some offices can do impact testing (computer software) to measure improvement. You should get seen right away if any new neurological symptoms: weakness, numbness, gait disturbance..