Congrats on the move!

Just a quick thought, if the altitude is bothering you at 5k elevation, take a little time to read up on the symptoms of Acute Mountain Sickness(AMS) and the warning signs of HAPE and HACE- high altitude pulmonary and cerebral edema, respectively.

Seems like you are sensitive to altitude, so it never hurts to be prepared. hydrate frequently, like Desert Fox said, and I recommend picking up a bottle or two of oxygen shots- just an aerosol can of pure oxygen, a puff or two into the nose and mouth if you start getting dizzy or nauseous goes a long way. If you are out on a trip to higher elevations, the best way to get rid of symptoms is to just head down before it gets worse.

Enjoy the trails!