Razor burn is not a
chatzitzah (barrier). It presents no impediment to mikveh immersion, so you need not be nervous.
Cuts and wounds in general are not
chatzitzot as long as they are exposed (i.e., not under a dressing) and cleaned for immersion. It is also customary to soften scabs through the
bathing process prior to immersion.
Please write back with any further questions.