what is wrong with my calf muscles???

Hi all, Stef here. So I don't know what the hell my problem is but I cannot briskly walk or run for more than 1/4 of a mile before the outside of my calf muscles feel like they are being saturated with battery acid. I went an bought 120 dollar shoes to help the pro-nation I already suffer from and hoped that it would also correct my burning muscles. The thing is people, is that I can ride the bike forever... I feel like my legs never ever get tired when I'm on the bike. Walking fast or running on the treadmill for 15 minutes makes me want to cut my legs off. The outer part of my calf muscles just start burning and cramping. Any ideas? I tried WebMD but found that according to that website, no matter what is wrong with me, I am dying or should go to the hospital immediately. Let's be honest, I'm not dying. I'm fat, maybe my little calfies are just saying wtf are you doing putting all of this weight on us? For that I apologize to my calf muscles, but seriously, if you don't buck up, I will be dying from being a huge huge person. I will also probably become a diabetic. Guess what happens when people get diagnosed with diabetes? They run the risk of getting their legs amputated due to poor circulation... so seriously calf muscles... if you don't start working, you'll be the first to go. I swear.

Hopefully that little talking to motivated them. I'll keep you all posted on the issue.