Welcome to health care magic.
1.The history suggest that you have relived a bluster which is present on the scrotal sac. Could be of infective cause, hair follicular infection.
2.Inthis case if you are my patient i would have examine the
scrotum and skin palpation if any thing suspicious feels like inside to scrotal sac, an
ultrasound will be indicated.
3.Ultrasoun will give clear picture of where the blisters are present and if there is any communication internally.
4.At the same time condition of testis, free fluid, vascularity, chord and vessel status.
5.Superficial infection can be treated with a course of antibiotics, and maintain local hygiene. Do not press or scratch the blisters as you may complicate the condition.
6.Clean with antiseptic liquid and apply ant inflammatory cream locally for quick relief. Good luck.
Hope i have answered your query.
Any thing to ask do not hesitate. Thank you.