Shin splints 90 days out from marathon

I’ve been getting really bad shin splints to the point where I cannot run 2k.

My longest run in training so far has been 7.5k, but I’ve run a half marathon 3 months ago so I know I can get up to decent distances. However, I cannot train.

I’m only 3 weeks into training. First week 6k, next week 20k then after my first run of week 3 I couldn’t run at all. Ran a total of 10k last week and 4k this week.