I had to walk in freezing rain yesterday and I felt fine all day but in the evening I had sudden body aches. I feel worse now. Should I go to doctor?

Might Be Too Early. Given your exposure to the cold and new onset body aches it is likely that you might be coming down with a viral infection/cold. If your symptoms are limited to body aches, there is not much a doctor is going to do other than suggest symptomatic treatment: increased rest and hydration. If symptoms acutely worsen over next few days then you might consider seeing a doctor then.