Claire, regards to running-
Do your stretch first, and after? Very important. My downfall was my Achilles heels. I now do various leg, calf and thigh stretches, and stand on a step and drop your heel down, taking turns on each. Another good one is where you lift your foot/heel back to touch your bum cheek, good for front of thigh stretch.
Is the pain in your shins or calf?
Any pain in your feet?
What trainers are you wearing? A good basic trainer is New Balance. My first pair where £23 I think.
But I did a check on if I were flat footed or high arch etc. Have you done this, it's a must if you are serious.
Or have you gate etc done at a shop like Sweat Shop or a running shop. It's free, and they do your arch, and put you on a treadmill to see if your ankles turn in, out or neutral.
I started running in Feb last year at 31, age is not a problem, unless health of some sort of injury etc.
I will try find the link for a webpage. Don't give up, but do stretch.