I got a concussion 5 weeks ago and hit my head again today (back of the head) by kneeling and then getting up and hitting cabinet door. is this dangerous to hit head again so soon? i just got a headache in the spot that i hit today.

Yes and no: Most head strikes do not end up in concussions, it since your 1st one did, your brain is still sensitive for several months. The 2nd hit you described does NOT sound dangerous, but more like hitting a ‘sore’ part of the body. Physical pain, but not damage! In the meantime, follow a schedule, get proper rest, exercise, eat healthy, avoid alcohol and sedating medications (unless prescribed).