I have "pes planus" or flat feet and it is very difficult to run without a good pair of shoes. My last pair(which I ran the LA marathon with last year) were NIKE LunarSwifts but are totally worn out now. I've only ran one marathon and I have 2 marathons this year and since the last shoes were given to me, I've never had to pick out shoes. What are some recommendations? I need some with good arch support