Crash and burn - game over?

Well, I either have a bad case of anterior shin splints or even possibly small stress fractures in my left leg. My left shin is visibly swollen and even a short, easy 3 mile run on Tuesday was painful. I've decided to not run at all until it's better. I'm trying ice, elevation and Advil for a few days and if it doesn't improve then I'll get it x-rayed. Either way this brings my training to a screeching halt - possibly for weeks. So, I'll probably have to skip the Lake Chabot Trail Challenge on June 3rd. Looking ahead to the SF Marathon in July, I probably have to give up on my goal of running the full Marathon in 4 hours or less. Depending on how things progress, I may run the Half Marathon or run the Full Marathon with the goal of simply finishing - regardless of time. Of course, if I'm unable to run the Full Marathon in July there will be others. There is the Portland Marathon in October..;-)
Hopefully, I'll learn from my mistakes. I was impatient and training too hard. Most of my runs should have at ~10-minute mile pace - including all my long runs and all of my easy recovery runs. I was running most of my mileage at 8:30-9:30 pace mistakenly thinking that my legs wouldn't know the difference. I sort of assumed that my cardiorespiratory system would be the limiting factor and that my legs could handle anything. As it turns out my 46-yr old legs haven't been up to the demanding runs I've put them through. So, I'll recover and start training again - hopefully smarter next time...