Ceeteefeebs, hay you know what, I also have been taking a antihistamines,(was) because some outdoor bug bit me three times on the lower leg, and the Doctor recommended (walk in Clinic,at the time) Benedril for the rash and to reduce the swelling (allergic reaction to the bite).
Any hew I have noticed similar reduction in swelling down under, I don't know, But when I see my Gastro Doc Sept 24 I will ask her about it, I suggest you ask your Doctor too, I would love to know your Doctor's opinion on it too.
Try not to think to much about it until you see your Doctor and ask them.
Take care.