I think that a sex therapist (if your psychiatrist is not one) would be your best option for professional help. It may be helpful for your sexual partner (if the two of you are comfortable with this) to be involved, also. The use of, and choice of medication is certainly one that your therapist is in the best position to decide.
It sounds as though your problem will not be cured quickly and I would urge you to not panic and try to set reasonable expectations for yourself.
You might resubmit your question to Dr.Epp in the sexuality and Relationship forum to hear another opinion.
S.A. Liroff, M.D.