Why do you think that two of your ewes are empty? Were they scanned? We don't scan and sometimes we have ewes who don't look in lamb at all, then one day out pops a lamb! What I'm saying is that if you're not positive they are not in lamb, don't cut their feed to a bare field. We tend to just wait and if by a few days after the last possible date of lambing (counting from when the tups came out) there's no lamb,
then we judge her empty. In 24 years we have only had a couple of genuinely empty ewes, and they have lambed in subsequent years. If your ewes are empty and have been eating with the in-lamb ewes then they may be a bit tubby by the end but there's plenty of time for them to get back to normal before tupping time.
If your ewe with the dead lamb was still retaining her placenta after 2 days, then we would give an antibiotic - not a general one that you might keep in stock, but a specific one prescribed by the vet. This would cover her until she does cleanse. I see that she has cleansed now, so info for next time.
Cheer up, losing your first lamb is so sad, and you feel for the ewe, but she will stop grieving, usually a couple of days after birthing. Once you have live lambs bouncing around, that little dead lamb will just be a small black spot in your memory
Cross posted with Sally, slightly different times suggested for giving antiBs, just go by what your vet suggests.