shivering and other symptoms...

Our dear 6 year old schnauzer has been plagued with a variety of issues. She has allergies. She was also dignosed with glomularnephritis  about a year ago. Since then, she has been on a specialized diet and a dosage of enacard. She is tested frequently to monitor kidney functions. All of her numbers have improved significantly over the past year. Recently, however, she began acting a bit lethargic. We also noticed that her water consumption had increased a bit. Again.. she was tested and the kidney profile looked good. Her ALKP, however, was a bit high. The vet was not overly concerned with this number and suggested that we just monitor it in the future. This number was very high a year ago... when she was first being diagnosed.
Anyway, she is eating great. Her activity seems to have slowed some but, she remains alert and playful.  ;Perhpas the slowdown is just age. She seems most energetic in the evening, but of course this coincides with her "mommy" being home from work. The most distressing symptom we have noticed, however, is her shivering. We live in Florida, so it is hardly due to cold. She seems to shiver when excited... or sometimes just randomly. It does not last too long.... and does not seem to bother her much. We typically respond to it, by giving her a treat, hoping it will calm her. This, or any other distraction (taking her for a walk or throwing her a ball)... and the shivering subsides.
Still, we are worried.
Any thoughts??
Thanks!!!