Welcome to health care magic.
1.There is no possibility to get a sperm stuck in the scrotal skin. Possibly you have misheard to the doctors words.
2.The possible cause could be sebaceous
cyst / collection in the subcutaneous plane - which is usually painless and needs monitored, no intervention needed unless any discomfort is there.
3.The other possible cause could be subcutaneous inflammatory changes, hair
follicle infection - presents with pain and
redness / sore.
4.The remedy in this case - do not squeegee the lesion, press, scratch the area as you may complicate.
5.Maintain local hygiene and clean area with antiseptic liquid that will help to avoid further infections /
allergy. Good luck.
Hope i have answered your query,
any thing to ask do not hesitate to ask.
http://doctor.healthcaremagic.com/doctors/dr-ganesh/62888