Thanks for the query.
Sometimes in pregnancy constipation
can be seen.
Straining due to constipation can lead to skin damage around the anus and possibly that may be causing the problem.
Anyhow better to consult gynecologist once and get examined as during episiotomy skin incision
may extend into that place.
If there is any possibility of infection, you go for local antibiotic
cream there with your doctor's advice.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429