I finally had my foot checked up by a rehab doctor, and it felt like going into the Principal's office. Doc literally scolded me for running 10k without training and running 10k again on an injury. She said I had to respect the pain. Scary si Doc.. Principal's office talaga.
Turns out, I have plantar fasciitis on my right foot. My leg and foot muscles weren't strong enough to handle the distance I ran. I'm currently going through a series of physical therapy to help relieve the pain so I could get back to running. Doctor's recommendation: no running for two whole weeks while on PT. :( My PT also mentioned to avoid using flat shoes all the time, especially those without arch support. Walking in heels actually helps relieve the pain from plantar fasciitis (but gives you a different kind of pain on your toes hahaha). She noticed that my arch "falls" when my foot is flat on the ground (in other words: I seem to have an arch when my foot is off the ground, but it becomes flat when it's on the ground). Thus, as much as possible, I have to wear shoes that support my "fallen" arch.
Lesson learned, therefore, is to train properly for each running event. Especially when you're running the longer distances. You can probably handle the endurance required for the distance, but your muscles will suffer and will be very prone to injury.
Looking at the bright side, however, I got an excuse for my most recent purchase. I got FitFlops! I think that was what my PT was subtly telling me... HAHAHA :D Check this out:
The common flip-flop actually accentuates pronation, the rolling in of your feet which causes fatigue and biomechanical stress in your feet and lower legs. This can lead to overuse injuries like plantar fasciitis and posterior tibial tendonitis which are commonly known as "arch fatigue" or "fallen arches".
The "FitFlop" is engineered much like a "barefoot technology" shoe. It makes the muscles that stabilize the foot work harder, and over a period of time can actually strengthen your feet. FitFlops have a thick midsole, which encourages wearers to use feet and leg muscles more efficiently while walking. Research conducted by the manufacturer has shown that this thick midsole works the gluteals, hamstrings, thighs, and calf muscles more.
Talk about effective marketing! HAHA :) These sandals are not cheap at all, so they better work like what they advertised.
Stay safe everyone! :)