Can finasteride cause weakening of muscles and effect daily functioning?

Finasteride effects the testosterone and dihydrotestosterone levels in the body. It is not completely understood how these hormones effect muscle mass, however it is known low levels of both of these hormones can lead to loss of muscle mass.  Now that being said, it might not be the complete cause of what you described. I recommend getting a formal consultation with a hair loss expert. The are alternative options including PRP and progesterone injections to the scalp and/or hair transplantation.  Best, Dr. Emer.

Finasteride blocks transformation of testosterone to DHT. This brings about less DHT (which causes hairloss), and more testosterone circulation in the blood. So I am puzzled by your symptoms. You should definitely get a physical and evaluation by a doctor who has experience with finasteride as soon as possible. 

You may have Post-finasteride syndrome, occurs in men who’ve taken finasteride to treat hair loss by a chance of %4-5. That may causes some symptoms include: loss of libido, erectile dysfunction, depression, suicidal ideation, anxiety, panic attacks, Peyronie’s disease, penile shrinkage, gynecomastia, muscle atrophy, cognitive impairment, insomnia, severely dry skin and tinnitus. The condition often has a life-altering impact on victims and their families, such as job loss and the breakup of marriages and romantic relationships..