Physical position symptoms and conditions

I am a 57 year old man, who has been suffering from asthma several years. This spring my doctor put me on Singulair as an additional medicine to my cortisone-inhalator. after one month I feel symptoms of depression an mood-changing, severe ups and downs.
AND - as an additional symptom i have partially lost my feeling in some fingertips, and now parts of my left thumb and even a feeling of "cold2, mostly in my left hand.
anyone who share that symptom?
M.