I don't know what to do

I'm at a loss and close to giving up. Not on losing weight, but on running.  No, I never had aspirations of being a "real" runner, but I had aspirations of finishing this half marathon in 7 weeks with at least a 15 minute mile combo of run/walking.

But I can't even go half a freaking mile without ridiculous shin splints in my left leg. I used to do under 15 minutes a mile for at least 3 miles. Now I can't even do a 17:30 mile. I don't know what's going on. I have no idea. I stretch. I ice. I even got fitted for new shoes and they're clearly not working because they now hurt in a different spot on my right foot and today I got shin splints in my right leg.

I'm a miserable person after I try to run. Both emotionally and physically. I warm up with at least 2 minutes of moderate paced walking (probably 3.5 mph) and then do a 30 second run to 2 minute walk. I usually make it to my 2nd repetition before the shin splints kick in. Today I made it .62 miles before I had to turn around and come home. Walking. Slowly. I made it a whole 1.25 miles. At least Friday I made it 1.88 miles.

I've asked for suggestions from a health and fitness forum and while my post got 166 views, I got one whole response which didn't even come close to addressing my questions. I said that I stretch and she suggested stretching. So...

I've spent a lot of money registering for this half marathon - and that's not counting the travel and lodging costs as well as everything else that goes into it. If I can't do it, I don't know what I'll do. I don't know why I've regressed so much. I come home in tears and I keep trying and trying again. I can't take much more "rest" time. I have 7 weeks. And the furthest I've gone is 4 miles.

I don't want to give up, but I don't know what my options are right now.