Now A Days I Am Feeling That I Am Losing

Now a days i am feeling that i am losing my hand grip. And i can not lift weight. I am 46 years old. Last year i had lumber problam in L4 and L 5. because of that, i cannot walk well. Just i took bed rest for a month. Now i can walk, But other thing are increasing as i mention above. Please advice me, which doctor i have to consult?

Regards,

Munawar hussain