My Dauchsund Has Become Sluggish, Walks Very Slow. Will Sleep

my Dauchsund has become sluggish, walks very slow. will sleep in until 10 or 11 in morning moves slowly. has allergy to grass was just treated with prednisone shot and pills.( for 3 years now). had infection near vulva.recieved x2 antibiotics po and shots for that. but this lethargy has been going on for couple months now.she can't jump up on furniture nor run