Glad to hear she made the trip o.k., she went on Vacation!
You should be able to find Chick Starter or an All Flock feed at stores like TSC or similar.
I've used Purina in the past and those worked fine.
A lot depends on where you shop/what's available to you.
With only 1 Hen, then you'll...
Sounds like she's holding her own.
Ivermectin is effective when treating mites on the body and for SLM. It's not as effective for treating worms like it used to be.
Gapeworm is not that common. The symptoms you describe sounds more like an old hen that may have some ascites (symptom of...