whay do my shins hurt after a short walk?!

hi this all started roughly about 2 months ago when i had to pick up my girlfriends son from his school. the school is only about a 10-15 min walk away so its not far.
i was roughly about half way to the school and that's when i felt sudden pain in my feet and shins it really ached and it felt as though i have been walking for miles and miles when i haven't been!! and now i have pins and needles in my feet and hands if off to have an mri scan soon to see if that will pick up anything?
i just cant seem to walk very far without it hurting me to walk.
im only 35 med build no job due to me having panic disorder apart from all of this i am fit and healthy. i smoke don't drink.
just wondered what any of you guys think i could be?

many thanks for reading and replying.