I was diagnosed with Pityriasis Rosea at the beginning of my pregnancy, and also miscarried 2 weeks ago at 6 weeks. I'm not sure either if the miscarriage was caused by the skin condition or not. It started with the 'herald patch' on the bottom of my back and spread all over my stomach and boobs. I was so worried but my doctor said it wouldn't harm the baby. I started bleeding heavily so went to the hospital where they did a scan and showed me the baby's heartbeat! They told me the embryo was 'peeling away' from the wall of the uterus and that it could end in miscarriage, but they gave me an appointment to have another scan 5 days later. When I went back they said the baby had died. I have no idea if the pityriasis rosea contributed to the miscarriage, but I'm scared to try again now in case the rash comes back and I have to go through this again. As for the rash, it started to clear up very soon after the miscarriage and there's hardly any evidence that it was there, so I'd say all in all I had it for maybe a month.
I'm sorry for your loss too, it's a terrible thing to go through, and I hope you're ok. x