I cut scrotum with rusty razor while shaving I got my tetanus shot 5-9 months ago I washed it out with soap and water, hydrogen peroxide too. What now?

Seriously? Why would you ever use a rusty blade anywhere on your body--let alone on a sensitive area that would be seriously affected by an infection? Tetanus and washing are fine, peroxide not needed (dangerous?). Use a triple antibiotic cream (neosporin) as directed. Call your doctor asap if any swelling or discoloration of the area occurs. Next time you feel the need to shave--spring for new blades.
Ouch. If the cut is superficial just apply neospoin ointment twice a day for 3 days. If the scrotum begins to get red swollen or painful see a doctor asap.
Replace razor. Sounds like a manscaping mishap. Keep an eye out for swelling, redness or pus coming from razor cut. Otherwise, wash scrotum daily, let wounds heal and get a new razor.