Share away Esther! Tell us more - is this your first marathon? Paris is a great one - many of us on here are serial offenders. And it's a great place for a weekend too. I haven't signed up yet, because I haven't yet decided on my spring running plans, but I can thoroughly recommend.
Two things occur that you could mention to your doc. Do you hold a lot of tension in your shoulders when you run? That might explain the pins and needles if your shoulders are very tight. Secondly, it might have been hyperventilation - if you were 'overbreathing', that can cause pins and needles. And if you don't know what's happening it can get worse and turn into a full scale panic attack, which would explain the feeling of it spreading. But I'm not a medic and you're right to get it checked out.