Thanks for the replies!
I did a couple of runs in the shoes and I thought they were fine. I managed 6+ miles with no problems and figured they were great, no issues. On Sunday I did my first long run in them, which was 11.5 miles. Towards the end I had a niggling ache on the outside of my right foot, but I figured it was nothing much. It was a little sore that evening but the next day I had totally forgotten about it.
I tried to go to the gym the next day, and when I went to put my shoes on (the Glycerins) I could barely walk! They were pressing on a certain sore spot just around my ankle - I believe it might be my peroneal tendon? I tried my friend's trainers on, felt no pain. Hadn't felt any pain in the shoes I was wearing earlier. It was just when I wore my running shoes!
So anyway today I tried my trail shoes on and I could feel tenderness in the area but not as bad as yesterday. I decided to go to Up & Running and seek advice. The guy there got a load of different shoes for me to try on and they all seemed to dig in the same spot, so I figured maybe it was a coincidence and said I'd see how I went, and have a few days off.
I just got home from town and dug out my NB 850s, put them on and I feel absolutely nothing! No pain at all when wearing them. My boyfriend felt the Glycerins and said they were really hard at the back, no wonder they were digging in. But loads of the other shoes I tried on in the shop seemed to do the same thing, and they were all different brands.
I'm so confused. On the one hand I'm glad because at least I still have a pair of shoes I can run in without pain (although I should probably rest while this thing calms down anyway), but on the other, I know that the NB shoes aren't right for me. I've been told on two occasions having done a gait analysis that I'm definitely a neutral runner, and the 850s are a support shoe. Both guys I spoke to at the store pulled the same confused face when I told them I'd been sold 850s.
But then it seems to be the only shoe out of the ones I've tried on that feels ok.
Any suggestions? It's helpful to know that the 850s don't hurt at all, because I have that to go on as a starting point. It might be worth returning to the store (or maybe trying somewhere different) with that knowledge. After trying so many pairs on and them feeling just as uncomfortable, I started to doubt that it was the shoes at all.
One thing he did suggest was using heel inserts, and I did try some which minimised the pain. But I shouldn't have to do that to avoid shoes digging in.
If anyone has advice or insight it would be greatly appreciated! Sorry for the long rant.