There was mild injury to the scrotal skin at the base of the penis.The itching might be due to allergic reaction
caused by the instrument you used for shaving.
You please take an Antihistamine drug which relieves itching.You have to take Oral Antibiotic and also anti inflammatory drug for quick healing.
You can apply local cream like povidone
I have done lot of surgeries over the scrotum
It will be healed soon.