I wouldn't assume it's about the carbs - it depends what intensity you're using, are you lacking energy or simply sore?

I would first look more closely at what else will have changed with the diet, the micronutrients, salt/rehydration in particular. And you shouldn't be afraid to eat, trying to limit intake and exercise is quite stressful. Allow yourself to get a good grip on what to eat to maintain your current weight and activity Take the time to stand still, you can lose a lot more time if you misunderstand your body and move in the wrong direction.

Mostly though I'd say it's only a week and your body will adapt to burn fat better making the exercise easier. Spend some quality time stretching/massaging etc. If the soreness is worse or lasts longer next time then consider dropping back down to walking and build up your running again over time, it probably wouldn't take long to get back to being comfortable where you are now. Try and fit in more walking on your off days to help recovery. And at most, throw in another 50g carbs right after your run and see what happens.

And can I do something to get rid of the soreness or make it better without increasing carbs?

The thing that comes immediately to mind is a massage...

Loren Cordain outlines some decent suggestions for muscle recovery in "The Paleo Diet For Athletes: A Nutritional Formula for Peak Performance". (The title really should emphasize that it was designed specifically for Endurance Athletes, ...but nontheless, there are some good takeaways for those of us who are somewhat-lesser-than-Ironmen):

One great suggestion was to increase the intake of more alkaline-based foods post-exercise to counter the tendancy of the muscles to become more acidic with exertion. This could be as simple as a handful of raisins after your workout (Yes - raisins are very high in sugar, but they're also extemely high-alkaline). The other "non-carb" version of this acid neutralizing approach is to desolve a little baking soda in a glass of water. The only caution here is that this method can raise your overall sodium levels if it is frequently utilized.

There are several other suggestions in the text to combat muscle sorness and fatigue (the real premesis of the book), but these were the best two solutions that sprung to mind.

Just seems like too much cardio to me. But if you really wanna stick to doing that much running, then UP your carbs, don't decrease it.

I would be sore too if I had just ran for 3 months. You need to take a rest there champ. 3 months with no sleep cant be good for you. How did you go to the toilet?