I stepped on a rusty nail about 4 months ago. It pierced the bottom of my foot, I got a tetanus shot the next day and everything seemed normal, pain went completely gone after a week or so. Now, appr. 4 months later , the pain has come back, its not intolerable pain but some days it hurts worse then others . I can see where the nail pierced my skin and theres a small white blister looking around it. It is sensitive to touch when i put pressure right on it. What could this be/mean? Should I be concerned? Is this normal?