lower leg pain, numbness

Hey, I am starting over cycling after 10 years (kids, job etc.)Just turning 57. I Used to regularly ride 25-30 miles without any difficulty. Using same bike-drop down bars, Brooks leather sadle, installed new shimano pedals and SP shoes w/cleats. Have been riding for about 2 weeks and suddenly, my right leg below the knee has excrutiating pain. Feels as though the leg has a broken bone which is not possible. Pain occurs about 15 minutes after ride. Have not done any real distance 7-10 mi at most. My theory is that this some sort of nerve issue-advil provides only minimal relief. Stopped riding for 2 weeks. Today rode for about 4 miles and same problem only more severe. Could barely walk or put pressure on the right leg.
Never had this problem before. Bike shop installed cleats and pedals so my foot is straight ahead. In the "old days" my cleats were turned in slightly.
Can't find anything on the internet that specifically addresses this-anyone have an idea what the problem is or where I should look? The doctor will likely tell me to quit riding which is the dead last option.