Such symptoms can be related to problem with your vagal tone (vagus nerve).
Do regular exercise with proper nutritious diet at home.
Do the exercises that you can.. Slowly it will build up your stamina and strength and you can do difficult exercises later if you want.
Being regularly physically active is important.
Also drink enty of water.
Next Steps
For the orthostatic hypotension whenever you change postures from lying to sitting and sitting to standing. Count slowly till 30 in your mind while changing a posture eg sitting to standing. Your body will adjust in that much time and then start moving about. If you avoid the sudden change of postures till you start doing better, it will help you.
Health Tips
Good luck.