Oh, and one other thing - a couple of Ibuprofen 20 mins before you start can really help and I usually carry a couple of spare tablets with me on a long run and pop them about an hour and a half after the first ones !
Sound familiar ? It basically describes just about all of the above symptons in this thread and seems to quite simply describe what you (and I for that matter !) are all suffering. It's pressure on a nerve which runs down the inside of the ankle and into the sole of the foot. Repeated impact compresses this nerve and causes tingling, then numbness. There are a few suggestions about how to deal with it but no magic cure unfortunately. Personally, when this comes on during a run, I stop and wait until the feeling has come back into my foot completely then carry on. Doing this once or twice during a run usually stops it coming back again. Don't be impatient to get going again too quickly as it will just come back. Just stop your watch and don't beat yourself up about having to stop.