Quick update -I bought a range of socks, and tried putting duct tape over the seam on the inside of the shoe, but nothing seemed to work past about 10k of running.
I went to Sweatshop and bought new shoes last week. The guy spent a lot of time fitting then, and recommended a pair a size bigger than my old ones (and some moulded insoles).
I've run in them twice now. The first time (60 mins) they felt lovely, then last night they started hurting at about 80 mins in. When I took my shoe off the inside of my big toe was sore again. It's not exactly a blister, looks more like the skin is squashed up in that place.
I do have the option of taking the shoes back and getting another pair. But when I tried wider ones in the shop they felt like boats, and my feet felt like they were sliding around in them.I was actually worried I'd turn an ankle if I ran in them.Maybe I need to find somewhere in between. Or is the problem simply that the blister has not healed (3-4 months now) so if getting irritated each time.
The new shoes are nike. I don't know if they tend to be wide or narrow over the toes in general.
Thanks in advance for any further advice.