What am i suffering from?

I'm not exactly a new runner, been running 6 miles a week... until 2 months ago when i stopped running completely. but recently as i wanted to train for marathon, i started running 20 miles a week and only ran on weekends... after doing so for 3 weeks i start to feel pain in my shin and knee area... what am i possibly suffering from?

You have done to much to soon and are suffering from that. Nothing more.

you have simply overworked your musculoskeletals and the tissues are crying. A gradual progress to your goal would have been more appropriate.yelufem.