my husband has been a very fit and healthy man all his life until AD came along, to see him like he is now is heartbreaking.
I understand this completely, as my husband was always healthy, active, liked to be outdoors. I have to stop myself from wondering how long he could have had a good life if he hadn't developed AD. I always imagined he would have had a long active life somehow.
I do manage to take him outdoors most days, to either sit in the garden or we go out in the car which is wheelchair adapted.
He has had two spells of being unwell with infections which have seemed to cause downturns, and then a hip fracture led to immobility. It is difficult to know with any certainty that taking meds / stopping meds can cause improvement / decline, as there is no way to run a control with the same person at the same time. It could be that your husband's decline would have happened anyway, but it is another burden of worry that these diseases heap onto the shoulders of the carer, sadly.