Blood blisters

I coming from a long cycling background into triathlon, I've been running for about 4 months 2-3 times per week, usual runs include 2 x 6km 1 x 15km. plus once a month I run the same route of 27km, just trying to build base for an Ironman next June at the moment.

I'm getting blood blisters on my toes, I haven't popped any as i'm worried about infection. Anyways, I am seeing the old nail die underneath and the a new one growing under (not pretty), it began painful but not anymore really.

I running in Hokas, haven't tried my old Saucony's yet. The size is correct, I went to a running specific shop and tried On running & hokas, choose hokas, so the size doesn't seem to be the problem.....

is this a blending in period where I haven't run in so long that my feet are going through the pain process or is it the shoe style maybe!!!! is this of a concern? Any experiences out there would be great, thanks!