If its an injury its best to see a physio but give it time as most doctors will take pain which has lasted longer then 2 weeks more seriously then those that have suddenly started to flare up.
Maybe cut down or work in intervals for a while to get used to the trainers, asking your body to just adjust like that at the blink of an eye...unfortunetly though this works excellently for a machine (bike tyres don't work on a grassy road, change to those with more tread and problem solved straight away) being human doesn't work the same way and your body will take time to adjust.
When your sure the pain has gone and you go back to trying again, take things very slow: watch/listen out for any new pains and try to stay more aware of whats going on in your body, learn whats good and bad pain and how far you can take it before it results in no come-back when you stop (or even no pain at all when you run!).