Dear hopetobemom-
I cannot say what the discharge is without being able to examine. Day 3 embryos probably implant 4 days or so after transfer, and day 5 or day 6 embryos within two days. So I do not think this jeopardizes implantation and is not caused by lack of or loss of pregnancy
In the United States, these must be prescribe by a health care provider. The prescription can be submitted over the internet.