Aemila

I also have this issue, here are the tips my GP/podiatrist has given me:
1) get good quality running shoes that have arch support (I find Asics work well)
2) before you run, freeze a bottle of water. Then after exercising, stand on the frozen bottle and roll it back/forward under your foot.
3) see your physio/podiatrist/doctor often to make sure you're not doing any damage.
 
Best of luck